The level of work engagement is an important aspect of organizational culture. In this empirical study the relation between engagement and experienced professionalism of probation officers is investigated. Starting from ideal-typical theories on professionalism, a psychometric instrument for measuring experienced professionalism was developed and administered to a sample of Dutch probation officers. Two reliable scales could be constructed that account for 64% of the variance in work engagement. Of these, professional ethos (humanistic values) is the most important predictor of work engagement in probation. Professional facilitation (support from the surroundings), however, also contributes to engagement.