A sexual agreement is an explicit mutual understanding made between two partners about which sexual and relational behaviors they agree to engage in within and/or outside of their relationship. Factors that prompt male couples to form a sexual agreement and under what circumstances remain underinvestigated, yet are important considerations for development of couples-based sexual health and HIV prevention interventions. By using thematic analysis with qualitative dyadic data from a convenience sample of 29 HIV-negative male couples, the present study sought to describe the timing and investigate the context and circumstances that led male couples to establish a sexual agreement in their relationship at both the individual and couple levels, and by agreement type. Themes identified for when a sexual agreement was formed included within the first 6 months, and after 6 months in the relationship. Themes related to context and circumstances of couples’ sexual agreement formation were as follows: (a) desire for sexual exploration, (b) arisen circumstances or events with other men, (c) influences from past relationship(s) and/or other couples (i.e., peers), (d) to protect against HIV, and (e) purposeful conversations versus understood. Findings suggest HIV prevention efforts should include skill-building exercises to help improve communication and promote sex positivity within male couples’ relationships.