Students in higher professional education are prepared for high level professional practice. To be able to fulfil their future roles, their educational programs aid them in developing their professionalism. This paper presents the conceptual and empirical search for a measurement model on professionalism. Professionalism is a multifaceted construct which is at best vaguely described in previous research. It is here conceptualized through the conceptual model by Griffioen (2019) as a personal integration of professional identity, professional knowledge and professional action that transforms over time through accommodation and assimilation practices. These practices imply the development of the (future) professional. Additionally, initial findings of the development of professionalism in students during their 4 year undergraduate degree are discussed.