Background Self-identified lesbian and bisexual African-American women living in the southern United States are a relatively hidden subpopulation within the lesbian, gay, bisexual and transgender (LGBT) community. Existing research suggests that African-American lesbian and bisexual women are at high risk for sexually transmissible infections (STIs), but the sexual and reproductive health needs of this population are just beginning to be understood. Methods: We conducted four focus groups and five individual interviews with 24 lesbian and bisexual African-American women living in the Jackson, Mississippi, metropolitan area, recruited through the local STI clinic and through word of mouth. We aimed to characterise the role of two types of social organisations (lesbian families and noncollegiate lesbian sororities and fraternities) among the local LGBT community, and their influence on the sexual health of their members. Results: Both types of social organisations serve positive functions for their members. Lesbian families provide support and stability; this appears beneficial for younger individuals, who may lack support from biological families. Lesbian sororities and fraternities are visible due to their emphasis on community service, and offer a strong sense of solidarity and belonging. In both organisation types, discussions about sex were common, although members acknowledged a lack of information regarding safer sex among lesbian and bisexual women. Conclusions: Existing social organisations within the LGBT community, such as lesbian families and lesbian sororities and fraternities, should be incorporated into community-based popular opinion leader or lay heath advisor interventions in an effort to meet the sexual and reproductive health needs of marginalised populations. © CSIRO 2014.