Ancillary Studies

Over the years, Add Health Ancillary Studies have added a substantial amount of additional data for users, including contextual data on the communities and states in which participants reside, genomic data and a range of biological health markers of participants, and parental survey data. Past Ancillary Studies have added rich datasets to the Add Health archive that have been used by thousands of researchers and have greatly contributed to scientific knowledge.

An Ancillary Study is any study that derives support from independent funds outside the Add Health Study, and does one or more of the following:

        1. Merges secondary data sources to Add Health respondent records that requires unique identifiers (e.g., geocodes) to perform these linkages.
        2. Uses archived biospecimens collected by the Add Health Study to conduct new assays.
        3. Adds new survey questionnaire or biological data to Add Health, either through making additions to the core instruments during a particular wave or through the use of unique identifiers to collect new survey or biological data.

Add Health has established a set of requirements for investigators seeking to add ancillary contextual, questionnaire, or biological data to Add Health, under the auspices of an Add Health Ancillary Study. Most simply, Ancillary Studies involve: 1) writing an ancillary study proposal to Add Health and getting that proposal reviewed and approved by Add Health, and 2) the understanding that investigators who conduct an Ancillary Study must cover all costs incurred by the study, such as selecting special samples; collecting, processing or shipping biospecimens; preparing and documenting analysis files; integrating ancillary data into the Add Health Study; and archiving excess biospecimens. An Ancillary Study must be reviewed and approved by Add Health before a grant is submitted for external funding.

Please note that the review of Add Health Ancillary Study proposals is both time-consuming (on the part of Add Health) and serious. We not only consider such reviews to be similar to those of an NIH Study Section (e.g., Five Dimensions of Scientific Merit), but we also give serious consideration to both Add Health priorities and policies and to the scientific priorities of our main funding agencies over the years, particularly the Division of Behavioral and Social Research of the National Institute on Aging (NIA) and the Population Dynamics Branch of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). For further information on our review of Ancillary Study Proposals, please see our document entitled “Researcher Guidelines for Ancillary Studies,” also available on this website. 

Although Ancillary Study investigators are not required to have previous experience with the Add Health Study, demonstrated familiarity with Add Health data and study design will significantly enhance review of Ancillary Study proposals, within both Add Health and independent funding agencies.

Application Process

The development of an Add Health Ancillary Study proposal is time-intensive. Ancillary Studies also may be costly; make sure to read the Researcher Guidelines for Ancillary Studies carefully. Once submitted, Add Health will review and then either approve, reject or request modifications to Ancillary Study proposals in a timely manner (generally within 12 weeks).

General Requirements For Add Health Ancillary Studies

Ancillary Study investigators must meet the following criteria:

  1. Have a PhD, MD, or other terminal degree.
  2. Hold a faculty appointment or research position at their institution.
  3. Work for an institution of higher education, a research organization, or a government agency.
  4. Have an institutional review board (IRB) that complies with applicable Federal regulations governing research involving human subjects.
  5. Demonstrate completion of research ethics training by all research team members who will work with the Add Health data or biospecimens.
  6. Have a demonstrated record of using sensitive data according to commonly accepted standards of research ethics.
  7. Investigators proposing to conduct an Ancillary Study must cover all costs incurred by the study, such as: sample selection; collecting or pulling samples from archive; processing and shipping biospecimens; preparing and documenting analysis files; integrating ancillary data into the Add Health Study; and archiving leftover biospecimens. Some of these activities can only be performed by the Add Health staff and/or the Add Health archive lab, which must be paid for by the Ancillary Study.

Before Considering an Ancillary Study

  1. Review codebooks for existing Add Health datasets.
  2. Review the Add Health Completed and Approved Ancillary Studies table.
  3. Review published manuscripts for potential overlap with your proposal.
  4. Contact the Ancillary Studies Coordinator at with any questions or concerns.

Applying for an Ancillary Study

  1. Submit a brief (1-page) Concept Proposal for Add Health review.
  2. Address feedback and resolve issues from the preliminary review.
  3. Submit the Add Health Ancillary Study Application Form.
  4. Work with the Ancillary Studies Coordinator to develop a cost estimate.

After Approval

Upon completion of the review process, Add Health will send the Ancillary Study investigator
formal written notice of its decision to approve or reject the proposed study. The approval
notice will document Add Health’s support for the project and guarantee its collaboration.
This notice should be included in any external grant application to fund the project. If the
Ancillary Study is approved and funded, the principal investigator (PI) will be required to
complete the following distribution agreements prior to the release of any data or
biospecimens by the Carolina Population Center (CPC)/University of North Carolina:

  1. Review, fill and sign the Data and Material Use Agreement.
  2. Go to the CPC Data Portal and apply for a Restricted-Use Contract.

Additionally, the ancillary study PI will be required to submit:

  1. Proof of completion of research ethics training by all research team members who will
    work with the Add Health data or biospecimens.
  2. Proof of completion of HIPAA training by all research team members who will work with
    the Add Health data or biospecimens (if applicable).
  3. IRB approval for the ancillary study.
    Upon approval, the study budget will also be finalized and provided.

Review Timeline & Approval Process

All Ancillary Study proposals will be reviewed by the Add Health Review Committee. Requests to collect new biospecimens or to use archived biospecimens or biological data will also be reviewed and approved by the Add Health Biology Team.  Since reviewers may have questions or comments and more than one round of reviews may be required, applicants are strongly encouraged to submit proposals at least eight months before the anticipated funding agency’s submission deadline.  An Ancillary Study must be approved by Add Health before a grant to support it is submitted for funding.             

The review committee meets monthly on the first working Tuesday of the month to screen proposals. Proposals must be submitted by the last working Friday of the previous month to be included in that month’s review meeting agenda.  Applications that pass the screening are then assigned to reviewers.  Review feedback is discussed at the monthly review meeting and a decision is made.  Applicants will then be informed of the outcome (approval, revise and resubmit, rejection).  Additional information and clarification may also be requested.  The review process typically takes 6-8 weeks.  If a study is rejected, the investigator will be notified of the reason for the decision. Once an Ancillary Study is approved, changes in the scope or procedures of the study must be approved by Add Health.

Annual Study Progress Reports

After an Ancillary Study is funded and initiated, the PI is responsible for submitting annual progress reports on the status of the study to Add Health until Add Health has released final ancillary data. These progress reports must summarize the study’s activities, including:

  1. Data/specimens collected to date.
  2. Assays and analyses in progress or completed.
  3. For studies proposing to use DNA or other biospecimens, information on biospecimen use and storage.
  4. For studies proposing to use DNA, details of the polymorphisms genotyped and methods proposed to be used.

To facilitate annual reporting, annual report forms will be sent by the Add Health staff to Ancillary Study investigators on June 1 of every year in the study period. These forms must be completed and returned to CPC no later than July 1 of the same year. Ancillary studies that fail to comply with the annual reporting requirement may be ineligible for renewal of their Add Health restricted-use contract and/or their Data and Material Use Agreement.

Publication of Results

  1. Results from the Merging of Secondary Data onto Add Health Data
    Secondary data to be merged with Add Health data must be linked to the existing Add Health longitudinal data and released by the Add Health Study staff to the scientific community of Add Health users before any manuscripts, abstracts, or presentations derived from the Ancillary Study may be submitted for review. Any such manuscript, abstract, or presentation shall include appropriate attribution to Add Health, as specified in the Add Health restricted-use data agreement.
  2. Results from the Use of Add Health Biospecimens
    Subject to the terms of the Add Health Data and Material Use Agreement, Add Health shall not release ancillary data resulting from the use of Add Health biospecimens to the scientific community of Add Health users for a period of one year beginning upon release of the final, clean data file to the Ancillary Study PI. During this one-year period, the Ancillary Study PI may create and submit manuscripts, abstracts, or presentations regarding the Ancillary Study, with appropriate attribution to Add Health, as specified in the Add Health restricted-use data agreement.

Guidelines for Add Health Biospecimens

Parsimonious use of biospecimens is an important consideration in review of the Add Health Ancillary Study proposals. Add Health maintains a repository of biospecimens that were collected at various timepoints during the study. These biospecimens are finite and have the potential for critical scientific advancement. Thus Add Health has the dual responsibility of encouraging and supporting ancillary studies that utilize stored biospecimens, while also ensuring that there is a small reserve of biospecimens set aside for research purposes that simply cannot be foreseen at the current time. For this reason, Add Health has created two types of biospecimen reserves: 1) Restricted-Use Biospecimen Reserve, and 2) Future Opportunities Protected Biospecimen Reserve. For more information about these two biospecimen reserves, please review the Biospecimen Reserve Policy.

Prior to submitting a biospecimen Ancillary Study investigators should:

  • consult with their proposed laboratory before submitting an Ancillary Study proposal
  • determine the smallest possible biospecimen volumes needed to complete their proposed work
  • only request those minimum volumes
  • only run samples in singleton, when appropriate

With sufficient scientific justification, Ancillary Studies are limited to the following biospecimen volumes, including any necessary “dead volume” or padding:

  • 250 μl serum
  • 250 μl plasma
  • 1 μg DNA

Requests for larger volumes must be accompanied by additional, compelling justification.

Steps for Add Health Ancillary Studies Involving Biospecimens

1. Review and approveAdd Health review and approve the ancillary study, its biospecimen selection criteria, and volumes as well as internal quality control protocols.
2. Develop a pull listThe Ancillary Study PI (or designee) and Add Health work together to create a participant biospecimens pull list based upon approved selection criteria and Add Health standard biospecimen volumes.
STEP 2b: Add Health interleaves 5% non-participant biospecimens in sets of masked duplicate pairs in the pull list.
STEP 2c: Add Health interleaves 100 participant biospecimens from the second Intra-Individual Variation (IIV) visit into the pull list.
3. Create a pull listAdd Health creates a pull list using a biospecimen ID and a lab/vial ID. The pull list includes all participant, non-participant, and IIV biospecimens. Add Health securely and solely maintains the crosswalk from the biospecimen and lab/vial ID to the participant and non-participant IDs.
4. Prepare Storage Lab for Pulling BiospecimensAdd Health sends the pull list to the storage lab and has the storage lab pull and assemble the masked participant, non-participant, and IIV biospecimens. The storage lab documents the box/rack locations as they prepare biospecimens for shipment.
5. Send the Biospecimens to Ancillary Study LabThe storage lab sends the biospecimens to the ancillary study lab and sends a manifest to both Add Health and the ancillary study lab.
6. Testing and quality controlThe ancillary study lab performs testing. When finished, the ancillary study lab sends results to Add Health linked by a lab/vial ID.  The ancillary study lab also sends QC data and internal quality documentation to Add Health for review.
If the lab internal quality documentation is approved, move to STEP 7.
7. Replace Lab/Vial ID with Preliminary IDAdd Health replaces lab/vial ID in the results with a preliminary ID.  Add Health also removes non-participant and IIV biospecimen data so that only participant data remain. Add Health retains the crosswalk between the preliminary ID and the AlD.
8. Distribute preliminary dataAdd Health makes the preliminary ID-identified participant data and internal quality control documentation available to ancillary study investigators for analysis only.
Per Add Health policy, publication remains prohibited until after
STEP 10.
9. Evaluate data qualityAdd Health externally assesses data quality based upon the participant, non-participant, and IIV biospecimens.
If the external quality is high, move to STEP 10.
10. Analysis and publicationUpon satisfying the ancillary study protocols, Add Health exchanges the preliminary IDs for AIDs, then disseminates the AID-identified participant data and the internal and external quality control documentation to the ancillary study and Add Health user community at large, for analysis and publication.

Biospecimen Availability

WaveSerumPlasmaDNADried BloodUrineSalivaStool

Please note that Wave VI archived samples are not yet available and will not be available in the near future.  Applications proposing to use Wave VI archived samples or data will not be considered until further notice. 


Ancillary study proposals must clearly specify the selection criteria and sample size to guide biospecimen sample selection. Once an Ancillary Study has been approved and funded, the Add Health Biology Team will work with Ancillary Study investigators and Add Health programmers to develop the Ancillary Study’s sampling list, to develop its back-up sampling list, and to select the sample, all according to the approved study protocol. Any post hoc changes to approved Ancillary Study selection criteria, sample size, or protocol must be formally proposed and justified in an Add Health Ancillary Study Modification Request submitted to the Ancillary Studies group. Formal review and approval of such requests must precede sample selection. Given involvement of Add Health personnel in sample selection, associated costs must be fully anticipated and shouldered by the Ancillary Study. Costs must be negotiated with Add Health prior to the submission of Ancillary Study proposal to Add Health, which is also prior to submission for external funding.


Masking conditional on their availability, Add Health will randomly interleave quality control (non-participant) biospecimens totaling a recommended 5% of the selected participant biospecimens into the selected sample. The quality control biospecimens will include pairs of masked duplicates, thereby totaling 2.5% of selected participant biospecimens. For example, in a study of biospecimens from n=200 participants, Add Health will randomly interleave n=10 quality control biospecimens, i.e. 2 masked duplicates from each of n=5 non-participants. Any proposed reduction in the number of quality control biospecimens designated above must be justified in detail at the time of the Ancillary Study proposal.

After including the masked duplicate pairs, Add Health will interleave n=100 Intra-Individual Variation (IIV) participant samples, depending on their availability. Costs of assaying the masked duplicate and IIV participant samples also must be fully anticipated and shouldered by the Ancillary Study (or selected participant sample size reduced to offset them). Add Health will replace selected participant, non-participant masked duplicate, and IIV participant identifiers (IDs) with undifferentiable, masked Ancillary Study IDs before shipping samples to laboratories for assay. Add Health will control the crosswalk of participant, non-participant, and IIV IDs. Add Health will not identify participant assay results to Ancillary Study investigators until Add Health receives the results and associated documentation of internal quality control, as described below.

Internal Quality Control

Laboratories are expected to:

  1. Follow best practice when monitoring and controlling the quality of the assay data that they generate.
  2. Use conventional tools to do that, e.g. their own negative/positive controls, calibration standards, split samples, etc.
  3. Immediately alert the Add Health Ancillary Studies Coordinator by email at regarding any unanticipated changes in agreed upon lab protocol, reagent shortages, substituted materials, or adverse events that may affect sample integrity and/or assay quality.
  4. Provide documentation summarizing their procedures and assay data quality (including missingness; validity; reliability) when they return data to Add Health.
  5. Include conventional quality metrics in the documentation (including counts of missing values, differences in/correlations between known and assayed values, and within-/between-split sample coefficients of variation).
  6. Identify masked duplicate pairs (in studies requesting DNA for large-scale genotyping).

External Quality Control

Based on the above, Add Health programmers will produce, and the Add Health Biology Team will review an external quality control report. Costs of doing so also must be fully anticipated and shouldered by the Ancillary Study. The report will include standard reliability and validity measures. The report will substitute summary statistics for the above items among Ancillary Studies, generating high dimensional (e.g. omics) data. The Ancillary Study investigators can explore their assay results but cannot publish findings based on them until Add Health completes its external quality control analyses, sends the external quality control report to the Ancillary Study investigators, then after the (1) one-year exclusive research period disseminates the results, documentation, and report to the Add Health user community.

Submit an Add Health Ancillary Study

We are thrilled that you are interested in submitting a proposal for an Add Health Ancillary Study.  If you have not yet, please visit the Our Process and Guidelines tabs for detailed information about submitting your proposal.  If you are ready to move forward with a proposal idea, please send a one-page concept proposal to the Add Health Ancillary Study Coordinator at and our team will be happy to work with you on your submission.

If you have questions regarding Add Health ancillary studies, please send your question via email to:


The Add Health contract and data use agreement require that the following be included in each written report or other publication based on analysis of the Add Health data:

This research uses data from Add Health, funded by grant P01 HD31921 (Harris) from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), with cooperative funding from 23 other federal agencies and foundations. Add Health is currently directed by Robert A. Hummer and funded by the National Institute on Aging cooperative agreements U01 AG071448 (Hummer) and U01AG071450 (Aiello and Hummer) at the University of North Carolina at Chapel Hill. Add Health was designed by J. Richard Udry, Peter S. Bearman, and Kathleen Mullan Harris at the University of North Carolina at Chapel Hill.

If using the Parents (2015-2017) data, in each written report or other publication based on analysis of these data, use the following acknowledgement in addition to the above acknowledgement:

The Add Health Parent Study/Parents (2015-2017) data collection was funded by a grant from the National Institute on Aging (RO1AG042794) to Duke University, V. Joseph Hotz (PI) and the Carolina Population Center at the University of North Carolina at Chapel Hill, Kathleen Mullan Harris (PI).