Differentiated instruction is considered a prerequisite for the inclusion of students with disabilities (SWD) in general education. The aim of this study was to describe and evaluate the type and quality of curriculum modifications for SWD in Greek early childhood co-taught classrooms. Sixty-eight general and special education teachers in 34 co-taught classrooms participated in this study. The collection of data included 68 lesson plans with accompanying questionnaires and 57 classroom observations. The findings indicated that co-teachers plan and implement more 'instructional' than 'curricular' or 'alternative' modifications and that researchers' and co-teachers' reflections differ about the quality of the modifications (i.e. researcher instrument indicated low quality whereas teachers believed that their modifications addressed adequately the needs of the SWD). Further analyses relating to the impact of the students' and the co-teachers' demographic characteristics on the quality of the modifications are presented. The paper concludes with highlighting the implications of the study's outcomes and provides some recommendations for altering existing practices.