Physicians play a crucial role in providing smoking cessation counseling and medications. However, it is unknown whether individual physicians' approaches impact whether patients quit. We assessed patient quit rates within a national quality-improvement learning collaborative to document variation in quit rates at the physician, practice and health system level.We conducted a retrospective cohort study of primary care patients identified from the Optum analytics database, containing longitudinal ambulatory data for patients from 22 health care organizations between 1/2012 and 12/2018. We included smokers aged 18 years and above who attended at least three ambulatory visits, with two visits at least one year apart. Our primary outcome was abstinence for ≥12 months. We used a mixed effects logistic regression model to predict the probability of quitting as a function of patient variables. Quit rates were then adjusted by patient factors, and calculated at the level of clinician, clinic/practice and health system.Across all systems, 56% of patients had a documented smoking status in 2017. Among nearly 1 million smokers, 24% quit smoking. In the regression model, patient characteristics associated with quitting included older age, Hispanic ethnicity, being married, urban residence, commercial insurance, pregnancy, and a diagnosis of pneumonia, myocardial infarction, ischemic heart disease, cataract, or asthma. Medicaid insurance, low income, high body mass index, peripheral vascular disease, alcohol-related diagnosis, or chronic obstructive pulmonary disease were negatively associated with smoking cessation. Adjusted quit rates ranged from 14.3%-34.5% across 20 health systems, 5%- 66% among 1,399 practice sites and 4%-87% among 3,803 health care providers. Of smokers, 10.2% were prescribed smoking deterrents and 3.9% were referred for counseling.Smoking cessation rates varied substantially at the practitioner, practice site, and health system levels. It is likely that individual physician approaches to smoking cessation impact patients' likelihood of quitting.