Background: Teaching and assessment of professional behaviour (PB) has been receiving increasing attention in the educational literature and educational practice. Although the focus tends to be summative aspects, it seems perfectly feasible to combine formative and summative approaches in one procedural approach. Aims and method: Although, many examples of frameworks of professionalism and PB can be found in the literature, most originate from North America, and only few are designed in other continents. This article presents the framework for PB that is used at Maastricht medical school, the Netherlands. Results: The approach to PB used in the Dutch medical schools is described with special attention to 4 years (2005-2009) of experience with PB education in the first 3 years of the 6-year undergraduate curriculum of Maastricht medical school. Future challenges are identified. Conclusions: The adages 'Assessment drives learning' and 'They do not respect what you do not inspect' [Cohen JJ. 2006. Professionalism in medical education, an American perspective: From evidence to accountability. Med Educ 40, 607-617] suggest that formative and summative aspects of PB assessment can be combined within an assessment framework. Formative and summative assessments do not represent contrasting but rather complementary approaches. The Maastricht medical school framework combines the two approaches, as two sides of the same coin.