One of the impediments to teaching professionalism is unprofessional behavior amongst clinical teachers. No method of reliably assessing the professional behavior of clinical teachers has yet been reported. The aim of this project was to develop and pilot such a tool. Thirty-four desirable professional behaviors in clinical teachers were identified. Medical students (n = 13) and medical educators (n = 30) rated their importance and validity. Based on the ratings, 16 behaviors in 4 dimensions were included in an assessment form that was piloted in the Department of Pediatrics at McGill University, with medical students (n = 94) rating the professionalism of their clinical faculty (n = 20). One hundred and ninety forms were returned with between 1 and 22 evaluations per faculty member. Scores ranged from 25 to 48 (maximum rating = 48, mean score = 42.7, SD = 6.29). A generalizability analysis was conducted; internal consistency was 0.89, and reliability for a mean of 8.23 ratings per faculty member was 0.53. Inter-rater reliability for one item was 0.11, potentially due to the context specificity of behavior or low frequency of unprofessional behaviors. Exploratory factor analysis revealed 3 factors with eigen values over 1. Assessment of the professionalism of clinical teaching faculty appears to be feasible, acceptable and reasonably reliable. The explicit evaluation of professional conduct in clinical faculty could encourage the maintenance of professional behaviors and potentially decrease the effects of negative role modeling and positively affect the hidden and informal curricula.