The overall objectives of this project are (1) to evaluate the quality of the original male fertility records in the 1979-1996 rounds of the National Longitudinal survey of Youth (NLSY); (2) on the basis of this evaluation, to make adjustments to the data that should substantially improve the internal consistency and quality of the longitudinal data file; and then (3) to quantify the extent to which the data adjustments alter the basic profile of adult male fertility as well as likely macro- and micro-level analyses. The researchers will undertake a variety of internal data checks, utilizing in particular the multiple reports on fertility available for the children, related information on other non-biological children, and the detailed relationship information available in the NLSY data set. The final product of this project will include a public use data set including the revised data, a detailed description of the changes made, and an evaluation of the data quality, specifying potential biases in the original and adjusted data. The final report will also include suggestions for improved data collection in this area. The over-riding objective of this research is to provide researchers with improved quality data for examining male fertility and fatherhood issues for a contemporary national sample of American men. Paralleling this objective, the research will clarify, from a substantive perspective, the extent to which male data quality issues may be intimately linked with levels and changes in family structure; in particular the likelihood that the biological father is not in residence with the mother and child or that the biological father has followed other selected unstable relationship trajectories.