OBJECTIVES AND GOAL:: The objectives of this study were to examine the association between individual and partnership characteristics with condom use, sexual concurrency, and discordance in monogamy perceptions among out-of-treatment, young adult, drug-involved couples to gain a better understanding of how discordance in monogamy beliefs may influence HIV/sexually transmitted infection risk. STUDY DESIGN:: Data were collected from 94 predominantly black heavy alcohol and/or drug users (AOD) and their steady partners recruited through street outreach in Durham, North Carolina, and a methadone clinic in Raleigh, North Carolina. RESULTS:: One third was wrong about partners' monogamy intentions. Greater lifetime number of substances, longer relationship duration, and at least weekly relationship conflict were associated with inconsistent condom use, and discordant monogamy beliefs were associated with consistent condom use. CONCLUSIONS:: Many individuals misperceive their partners' monogamy intentions, although this misperception may be reflective of greater HIV/sexually transmitted infection protection. Interventions for couples should focus on strategies appropriate for committed long-term relationships, including increasing awareness of partner risk behavior, negotiating safety, and conflict resolution skills
