BACKGROUND AND OBJECTIVE HIV prevention counseling has changed behavior and reduced incident sexually transmitted diseases (STDs) in research participants. GOAL This article assesses whether counselor demographics or counselor-client dyad characteristics influenced prevention counseling in Project RESPECT as measured by intervention completion and incident STD after counseling. STUDY DESIGN We analyzed data from Project RESPECT, a randomized, controlled trial of HIV counseling interventions in STD clinics. RESULTS There was no significant association between client failure to complete the intervention and demographic characteristics of the 32 counselors or dyad characteristics. Clients who did not complete the intervention were significantly more likely to acquire a new STD infection by the 12-month visit than those who completed the intervention (adjusted odds ratio, 1.7; confidence interval, 1.2-2.4). There was no significant association between new STDs and counselor characteristics or dyad characteristics. CONCLUSIONS Counselor or counselor-client dyad characteristics evaluated in this study were not associated with intervention completion or the prevention of new STDs.