Seventy-three women attending a health fair completed a questionnaire that measured demographic and health history variables, knowledge, and current practice of breast self-examination (BSE), Multidimensional Health Locus of Control (MHLC; Wallston, Wallston, & DeVellis, 1978), and components of the Health Belief Model (HBM; Rosenstock, 1974) in relation to breast cancer and BSE. These variables formed the basis of a conceptual model of BSE behavior that was examined by having each woman participate in a behavioral trial with a breast model in which her BSE technique and ability to detect simulated tumors was assessed. Regression analyses revealed that self-confidence in the efficacy of BSE was the best single predictor of proficient BSE. Powerful others HLC, knowledge of correct BSE behaviors, and chance HLC, respectively, also contributed significantly to the variance in performance. As anticipated, successful lesion detection was most strongly associated with more proficient BSE technique and higher frequency of BSE practice in the past six months. Internal HLC scores were not predictive of either behavioral measure. Similarly, except for perceived efficacy of BSE, HBM variables showed no strong relationships to observed behavior.