HIV diagnoses among females in the USA declined 40% during 2005–2014 with the largest decline (42%) among Black/African Americans. African American females remain disproportionately affected. We explored contributions of STD rates and sexual risk behaviors among African American females, HIV diagnoses among potential male partners, and sexual risk behaviors and viral suppression rates among HIV-positive potential male partners to declining rates of HIV diagnoses among African American females. Results suggest temporal trends in the factors that increase HIV infectiousness and transmissibility within sexual networks, i.e., decreases in rates of other sexually transmitted infections among African American females, decreases in HIV diagnoses among potential male partners, and increases in viral suppression among heterosexual and bisexual HIV-positive potential male partners in care, may explain the decline. Findings highlight a need for future research that provides context to the sexual risk behaviors and sexual network factors in order to continue progress.