Urines were analyzed qualitatively for the presence of cocaine metabolite (benzoylecogonine) three times per week, since benzoylecogonine is detectable for about three days after co- caine use. Urine toxicologies were taken on the day of study entrance, thrice weekly thereafter for twelve weeks, and at the six month follow-up visit. Missed urines were addressed statisti- cally, as detailed under Statistical Analyses.