OBJECTIVE To identify factors that are associated with the scope of practice of FPs and GPs who have office-based practices. METHODS Secondary univariable and multivariable analyses of cross-sectional data from the 2001 National Family Physician Workforce Survey conducted by the College of Family Physicians of Canada. METHODS Canada. METHODS General community of FPs and GPs who spent most of their clinical time in office settings. METHODS Demographic characteristics and scope of practice score (SPS), which was the number of 12 selected medical services provided by office-based FPs and GPs. RESULTS The multivariable model explained 35.1% of the variation in the SPS among participants. Geographic factors of provincial division and whether or not the population served was rural explained 30.5% of the variation in the SPS. Male physician sex, younger physician age, being in group practice, greater access to hospital beds, less access to specialists, main practice setting of an academic teaching unit, mixed method physician payment, additional structured postresidency training, and greater number of different types of allied health professionals in the main practice setting were also associated with higher SPSs. CONCLUSIONS Geographic factors were the strongest determinants of scope of practice; physician-related factors, availability of health care resources to the main practice setting, and practice organization factors were weaker determinants. It is important to understand how and why geographic factors influence scope of practice, and whether a broad scope of practice independent of population needs benefits the population. This study supports primary care renewal efforts that use mixed payment systems, incorporate allied health care professionals into family and general practices, and foster group practices.