This quasi-experimental study evaluated the influence of structural intervention components (e.g., changing organizational and social influence factors) in reducing biological sexually transmitted infections (STIs) and reports of unprotected sex among female bar workers (FBWs) in the Philippines (N = 369 at baseline). Recruited from four large southern Philippines cities, FBWs were exposed to a standard care, a manager influence, a peer influence, or a combined manager/peer influence condition. After the two-year intervention period, FBWs in the combined peer and manager intervention condition showed greater reductions in STIs and unprotected sex relative to those in the standard care condition. FBWs in the combined and the manager only conditions also showed a decrease in STIs compared to those in the standard care condition. Managers in the standard care condition reported lower positive condom attitudes and lower attendance at HIV/AIDS related training sessions compared to those in the combined condition. The combined effect of managers and peers had a positive, synergistic effect on condom use behavior and STI reduction compared to the standard care. This research provides empirical evidence that structural changes such as rules, regulations, and increased accessibility of condoms must be in combination with normative changes (individuals' attitudes, beliefs and normative expectancies) in order to achieve the greatest benefit in condom use behavior and STI reduction/prevention.