Purpose: The first aim of this study is to explore to what extent communities of practice occur in the school workplace. The second aim is to explore the relation between communities of practice and diversity in composition of teacher teams. Design/methodology/approach: Quantitative as well as qualitative data were gathered from seven teacher teams in a school for secondary education. Questionnaires and observation instruments were used to measure and analyze teacher teams' collaborative activities and diversity in composition. Findings: Data suggest that communities of practice actually occur in the school workplace, but to a moderate extent. Also, communities of practice are related to four of the five diversity attributes that were investigated. Research limitations/implications: The current study is a snapshot measurement of communities of practice. Future research is recommended to focus on the development of communities of practice in the school workplace by including longitudinal measurements. Practical implications: Implications for teachers and administrators include follow-up activities aimed at stimulating and sustaining communities of practice as well as taking diversity considerations in team composition into account. Originality/value: Studies suggest that a community is a promising context for embedding collaboration into the culture of the school. However, empirical research that focuses on communities in the school workplace seems largely absent. This study provides insight in the occurrence of communities of practice from two perspectives: the perception of community members and the observation from outsiders. (Contains 2 tables and 1 figure.)