Predictors of intention to abstain from sexual intercourse or use condoms consistently with both main and other partners were investigated in 431 Puerto Rican high school students. The basis for this study was the theories of reasoned action (TRA) and planned behavior (TPB), and two predictors from the theory of interpersonal behavior (TIB). As suggested by the TPB, self-efficacy substantially increased the predictability of both intentions over and above the TRA variables (attitude and subjective norm), and was the only variable that significantly predicted these intentions with both types of sexual partner. Anticipated emotional reaction and past behavior from the TIB, and gender further improved the predictions, but their contribution depended on the specific intention and the type of partner. The findings suggest that an augmented theory of planned behavior could be useful for understanding intention to engage in precautionary sexual behaviors among Puerto Rican adolescents. (Contains 6 tables.)