Despite social-cognitive interventions to increase safer sex awareness, condom use among female sex workers (FSWs) continued to be inconsistent. To account for the possible influences of contextual factors that may hinder or promote FSWs' safer sex negotiation and condom use, the present study examined the effects of non-governmental organizations (NGOs), FSWs' managers, and clients on FSWs' negotiation efficacy and condom-use efficacy, and the effects of efficacy on condom use. One hundred and nineteen FSWs in Hong Kong completed a questionnaire that focused on their perceived influences of NGOs, managers, and clients toward safer sex negotiation and condom use. Hierarchical regression results showed that whereas NGOs' influence and clients' support were positively related to negotiation self-efficacy, managers' pressure, and clients' pressure were negatively related to negotiation self-efficacy. Managers' pressure was negatively related to condom-use self-efficacy. Logistic regression results showed that FSWs with high condom-use self-efficacy was 24 times more likely to use condom in the previous six months than their counterparts. The present study indicated the importance of social contexts in affecting FSWs' safer sex negotiation and condom-use self-efficacy. Implications on preventive programs for FSWs, managers, and clients were discussed.