Continuing gains against incidence of HIV and other unwanted consequences of unprotected sex requires deeper understanding of characteristics of condom usage among sexually active youth. The present study assesses whether partner trust predicts condom usage, and whether potential associations were mediated by general self-efficacy, among a cohort of sexually active adolescents in Meru County, Kenya. We also sought to discover associations between socio-economic status, psychological resilience and partner trust to increase understanding of trust towards one’s intercourse partner. Mediation analyses, stratified by gender, reveal that condom usage is predicted by self-efficacy and partner trust among females but not males. Higher psychological resilience predicts lower partner trust among both genders. Partner trust was lower among female respondents who were not literate, but did not significantly vary by literacy among males. Reported previous monthly earnings were not significantly associated with partner trust among males or females. The present findings support further study on partner trust, and its association with protective sex behaviors. Further, interventions targeting condom usage among females may benefit from actions to increase awareness of partner sexual behavior and increasing self-efficacy.