Two aspects of formative assessment practices in the Dutch and Flemish educational context were explored: the degree to which secondary mathematics teachers implement a variety of assessment techniques in their classrooms, and the extent to which their students are involved in assessment practices. By developing profiles based on the combination of these aspects of formative assessment, we were able to distinguish various developmental stages in teachers' implementation of formative assessment. Compared to their Flemish colleagues (n = 83), Dutch teachers (n = 120) used a wider variety of assessment techniques and stimulated student involvement in assessment more. Features of the educational context, such as the availability of teacher professional development for formative assessment, possibly influence development towards use of formative assessment practices in the classroom. The profiles can be used to inform teacher professional development initiatives, as they give insight into the current status of teachers' assessment practices.