Several instructional strategies have been recommended for use in heterogeneous classrooms, but the frequency of their actual use has remained largely unknown. Therefore, an electronic survey was sent to Finnish comprehensive school teachers (N = 2276) in order to assess the prevalence of three selected inclusive strategies: co-teaching, group work, and differentiation. The results showed that co-teaching was used by 42% and group work by 43% of the teachers at least on a weekly basis, while differentiation was used regularly by 83% of teachers. The application of all strategies was strongly associated with teacher category, with subject teachers using them less frequently than classroom teachers or special education teachers. There was a linear trend indicating that these teaching strategies were more prevalent in bigger municipalities and among younger teacher groups. Their use was also more prevalent among female than male teachers. Additionally, among classroom teachers, their usage was associated with a more positive attitude towards inclusive education. Among classroom and subject teachers, their use was also associated with a higher sense of teacher efficacy. It is suggested that subject teachers in particular need to use more versatile teaching strategies to strengthen their ability to cope with student diversity.