Background: Rates of contralateral prophylactic mastectomy (CPM) have markedly increased but virtually nothing is known about the influence of surgeons on variability of the procedure in the community. We quantified the influence of attending surgeon on rates of CPM and clinician attitudes that explained it. Methods: Population-based sample of 7810 patients newly diagnosed with curable breast cancer (BC) in Georgia and Los Angeles County treated in 2013-15 were surveyed (response rate 70%, n = 5018) and responses were linked to 488 attending surgeons through patient report. Surveys were sent to surgeons towards the end of the patient data collection period and 377 completed them (response 77%). We linked 3718 respondent patients with unilateral disease to 365 respondent surgeons. Two surgeon attitudes scales were developed based on a scenario of a patient with early stage BC at average risk of a 2^nd primary cancer: 1) favors initial breast conservation and, 2) reluctance to perform CPM if patient asks. We did multilevel analyses using information from patient and surgeon reports merged to SEER data. Results: A model including patient clinical factors and surgeon id predicted CPM extremely well as it explained 37% of the variability in the likelihood of CPM. Patient factors explained 16% of the variability but the surgeon identifier alone explained even more (21%). The odds of a patient receiving CPM increased 3-fold (95% CI 1.9, 4.7) if she saw a surgeon with a practice approach one standard deviation above a surgeon with the average CPM rate (15%). One quarter (24%) of the surgeon influence was explained by attending attitudes about initial recommendations for surgery and responses to patient requests for CPM. The rate of CPM was 34% for surgeons who least favored initial breast conservation and were least reluctant to perform CPM. By contrast, the estimated rate was 5% for surgeons who most favored initial breast conservation and were most reluctant to perform CPM if asked. Conclusions: Attending surgeons exert strong influence on the likelihood of receipt of CPM for breast cancer. Variations in surgeon attitudes about recommendation for surgery and response to patients request for CPM explain a substantial amount of this influence.