Research on the well-being of teachers was conducted at the request of the Department of Education in Flanders, Belgium. The goals were: (1) to construct an instrument for the Education Inspectorate; and (2) to conduct a survey in order to identify school-related conditions relevant for teachers' professional well-being. Based on literature and panel discussions with teachers and principals, a questionnaire was constructed, tested and subdivided in subscales following a factor analysis. The questionnaire was administered to a representative sample of elementary (covering both nursery and primary schools, children aged 3-12) and secondary school teachers. A multilevel analysis reveals how differences in scores can be explained at school level. (Contains 3 tables, 2 figures and 3 notes.)