Sexual partner types and partnership dynamics have important implications for condom use. Yet most HIV prevention research conceptualises condom use as individual-level rather than dyadic-level behaviour. Evidence of a generalised HIV epidemic in urban predominantly low-income US Black heterosexual communities highlights the need for a culturally and contextually-grounded understanding of partner types, partnership dynamics and condom use from the perspective of Black heterosexual men. We conducted individual interviews with 30 self-identified men between the ages of 18 and 44, 18 (60%) of whom reported at least two partner types in the last 6 months. Key findings include: (1) 'main and casual' partner types per the HIV prevention literature; (2) three casual-partner subtypes: primary, recurrent, and one-time casuals; (3) overlapping partnership dynamics between main partners, primary-casual partners and recurrent-casual partners, but not one-time casual partners; and (4) consistent condom use reported for one-time casual partners only. The study underscores the critical need for more condom promotion messages and interventions that reflect the dyadic and culturally-grounded realities of US Black heterosexual men's sexual partner types and partnership dynamics.