Scholars who study criminal and delinquent behavior rely on the self-report method for measuring crime and delinquency. Gang researchers also rely on the self-report method for determining gang involvement and measuring criminal and delinquent behavior of gang members. This study examines disclosure rates of recent drug use by gang members in comparison with their urinalysis outcomes. A substantial body of research indicates that members of the criminally involved population, at least those who get arrested, are less than accurate when reporting recent drug use; however, it does not appear that gang members are different in their reporting than members of the group as a whole. Disclosure rates of gang members did not differ significantly from those of non-gang members. This adds to the cumulative body of evidence that although not perfect, self-reports of illegal behavior are a valid measurement technique in gang research. (Contains 4 tables and 11 notes.)