Key Resources User Guides Detailed documentation designed to help users understand the study design, data sets, and guidelines for analyzing the data. Codebooks PDF codebooks for coding responses and documenting the layout and code definitions of the data files. Add Health Navigator Metadata discovery tool to explore and create custom codebooks, as well as provide a wave to wave variable comparison for Waves I-V. Public-Use Data Sets Access and download the public use codebooks and data sets which contain a reduced sample size (Waves I-V). Restricted-Use Data Sets Access the data sets available via restricted-use contract, renew contract, add researchers, and transfer or terminate contract. Data linkages are not allowable with a restricted-use contract. Ancillary Studies Submit an application to add new contextual or biological data to the Add Health data sets, including data linkages.