DESCRIPTION: This Core supports the work of the center by providing scientific leadership and professional staff who can effectively accomplish subject recruitment and data collection for center research projects. In addition to these basic function, this core also conducts research on various factors hypothesized to affect subject recruitment for prevention research. The personnel for the Core include five scientific leaders (Drs. Brae, Cialdini, MacKinnon, Michaels, and Millsap) and professional staff who carry out the day-to-day operations in terms of recruitment and data collection. In addition to serving basic research needs across all center projects, during the next five years this Core will develop and evaluate a preliminary theory of subject participation and retention in prevention research studies. The specific aims for the next five years are to: 1) provide center-wide services for sample projects, 3) quality control procedures for assuring effective interviewer/recruiter performance, and 4) continue the scientific study of participant acquisition and formulate and test a theory of how best to recruit participants in prevention activities.