Drug use trends are typically monitored by surveys of retrospective self-reports of drug use; yet we know little about the consistency of reports made across the life course. This study examines the consistency of marijuana self-reports from adolescence and adulthood and what characterizes inconsistent reporting among a cohort of African American first graders followed longitudinally from age 6 to 32 (N=599, 51% female). Self-reported lifetime adolescent marijuana use (ages 16-17) and retrospective reports at age 32 were combined to categorize respondents as consistent reporters of nonuse (22%), consistent reporters of use (42%), adult recanters (19%), adolescent underreporters (8%), and inconsistent reporters of age of initiation (9%). Overall, about 64% of the population were consistent in their reports of adolescent marijuana use from adolescence to age 32. Multivariate logistic regression analyses found that recanters reported less marijuana use as adolescents, lower parental supervision during adolescence, lower deviant behavior as an adult, and stronger anti-drug values as adults than did consistent reporters. Adolescent underreporters reported less assault behaviors and less alcohol use as adolescents and had lower first grade math achievement than consistent reporters. Family background, depression, criminal arrests, and the field conditions of the interview were not related to inconsistent reporting.