Colorectal cancer is the third most frequent cancer, yet screening rates for this cancer remain low. This study was designed to identify factors associated with family physicians' rates of recommending or providing flexible sigmoidoscopy. We applied a behavioral model consisting of three components: physician attitude toward providing the test, facilitating conditions, and reinforcing conditions. Qualitative interviews identified relevant measures of each model component and guided the design of the survey. The survey was administered to 60 randomly selected family physicians in Washington State. Chart reviews were conducted to measure physician rates of providing flexible sigmoidoscopy. All three model components were significantly correlated with sigmoidoscopy rate. Multiple regression found physician attitude, facilitating conditions, and their interaction to be significant determinants of sigmoidoscopy rate (multiple R = 0.72). Analyses of specific items used to measure physician attitude found that physician beliefs about cost, time, income, degree of distaste, risk of complications, and screening effectiveness were significantly correlated with sigmoidoscopy rate. Specific facilitating conditions found to be correlated with rate of providing the test included physician and staff training, availability of a reminder system, and clinic structural conditions. This study provides strong support for application of a theory-based model to understand physician provision of flexible sigmoidoscopy testing for colorectal cancer. The findings provide very specific information to guide development of educational and motivational efforts and modification of facilitating conditions to increase physician provision of sigmoidoscopy to control colorectal cancer.