The purpose of this study was to evaluate the separate and combined effectiveness of brief and intensive interventions for sexual risk reduction among patients at a sexually transmitted disease (STD) clinic. Patients (N =1483; 54% men; 64% African-American; M = 29.2 years old) were recruited from a publicly funded, walk-in STD clinic. Patients completed a baseline assessment, and then were randomized to one of six intervention arms; each arm combined a brief intervention with an intensive intervention. The interventions provided different levels of information, motivational counseling, and behavioral skills training, guided by theory, formative research, and empiric precedent. Follow-up assessments, including STD screening, occurred at 3, 6, and 12 months post-intervention. The results showed that infection rates declined from 18.1% at baseline to 4.5% at 12 months. At a 3-month follow-up, patients reported fewer sexual partners, fewer episodes of unprotected sex, and a lower percentage of unprotected sexual events; they strengthened sexual health knowledge, safer sex attitudes and intentions, and self-efficacy beliefs. No consistent pattern of differential risk reduction was observed among the six intervention conditions, nor was any evidence of decay from 3 to 12-month follow-ups obtained. We conclude that implementing behavioral interventions in a STD clinic was associated with significant reduction of sexual risk behavior and risk antecedents.