Objective: To investigate knowledge, attitudes and practices of oncologists towards physical 2 activity (PA) in cancer survivors, and the association between oncologists’ own PA behavior 3 and PA promotion. Methods: Oncologists (n=123) completed a survey based on the Theory of 4 Planned Behavior (TPB). Participants reported PA promotion behavior, PA involvement, 5 attitudes, intentions, social norm, Perceived Behavioral Control (PBC), confidence and 6 knowledge of exercise prescription. Structural equation modelling (SEM) evaluated these 7 associations. Results: Less than half of oncologists reported regularly promoting PA to 8 patients (46%), with 20% providing written information and 23% referrals. Only 26% were 9 physically active. TPB SEM pathways explained 54.6% of the variance in PA promotion 10 (CFI=0.905, SRMR=0.040). Social norm was the only significant pathway to intention, but 11 also a significant indirect pathway to PA promotion (p=.007). Confidence to promote PA, 12 PBC and intentions were direct significant pathways to PA promotion (p<.05). Exploratory 13 SEM pathways explained 19.6% of the variance of PA behavior, which in turn explained 14 13.1% Social Norm, 10.7% Attitude, 10.0% Confidence to Recommend and 17.8% PA 15 promotion behavior (CFI=0.921, SRMR=0.076). Instrumental-attitude was a direct significant 16 pathway to PA behavior (p=.001). PA behavior was a direct significant pathway to social 17 norms, attitude, confidence to recommend, and PA promotion (p < 0.05). Conclusions: 18 Oncologists reported a modest ability to promote PA, low PA promotion rates and limited 19 knowledge of exercise prescription. Patient physical activity promotion may be improved 20 through strategies that increase oncologists’ PBC, confidence and their own personal PA 21 participation.