Aim: To identify the factors that influence the time nurse practitioners (NPs) in primary care, home care and long-term care spend on activities in two Canadian provinces. Background: Little is known about how patient, provider, and organizational characteristics influence the time NPs spend when caring for patients in primary care. Methods: Time and motion studies (n=30 NPs, 829 hr, 14 practices). Data were collected in Québec from May 2017–May 2018 and in Ontario from March–November 2015. Descriptive statistics and linear regression analysis were completed. Findings: NPs spent 66% (Ontario) to 68% (Québec) of work time on clinical activities. Mean time spent by NPs in patient encounters in Québec varied by setting (long-term care: 13 min 21 s; primary care: 22 min 10 s; and home care: 26 min 25 s). In Ontario, time spent by NPs in patient encounters averaged 25 min 48 s in primary care. In Québec, significant associations were found between number of clinical and non-clinical activities, health maintenance/wellness visit, chronic illness follow-up, patient gender (woman), urban location, and multiple informants in the exam room and NP time spent on activities. In Ontario, associations were identified between number of clinical and non-clinical activities, chronic illness follow-up, NP gender (woman), and acute/minor injury and NP time spent on activities. Conclusion: Time NPs spend on activities differed depending on patient, provider, organizational and health system characteristics. NP activities cut across all role dimensions. The practice setting, number of clinical and non-clinical activities, and chronic illness follow-up were significant predictors of time spent on activities. Our study provides a comprehensive overview of NP activities and the factors that influence time spent on these activities while working in health systems with more and less restrictive scope of practice regulations, and with a wide range of patient populations in primary care.