Opposed to large nationally sponsored health initiatives or biobanks, little is known about gathering genetic samples from young adults participating in academic community-based epidemiologic studies of mental health and substance use, especially samples with a large number of minority participants. This study describes our experience of establishing a genetic arm within a longitudinal study of a cohort of young adults (mean age 29, 75 % African American, 58 % female). In total, 75 % of those interviewed in the most recent wave donated a DNA sample (31.6 % blood and 68.4 % saliva) and over 90 % provided consent for storage and sharing. Current smokers were more likely to donate a sample than nonsmokers (adjusted odds ratio (aOR)=1.59, 95 % confidence interval (CI)=1.14, 2.22). The odds of obtaining a saliva sample were increased for those who were former cannabis smokers and who drank more regularly, but decreased among participants with less education and a history with drug use. Fewer minorities (aOR=0.37, 95 % CI= 0.18, 0.75; p=0.006) and cannabis users (aOR=0.46, 95 % CI =0.27, 0.77) consented to sharing their sample with other investigators. Findings also illustrate there are many study parameters that are important in planning biologic collection efforts. Building strong rapport and trust with subjects, minimizing the burden involved by the respondent to obtain a biological sample, offering a choice to provide blood or saliva, and offering an incentive will increase the likelihood of obtaining a sample and, importantly, increase the opportunity to store and share the sample for the future.