Since the 1980s, a number of reviews on the impact of inclusion on students with special needs have been published (Madden & Slavin, 1983; Ottenbacher & Cooper, 1982; Wang & Baker, 1985; Hegarty, 1993). Results are equivocal, and several reviews point to a number of methodological challenges and weaknesses of the study designs within the included primary studies. In summary, most reviews suggest a neutral or small positive impact of inclusion on most outcomes. However, all reviews also point to the need to study the impact of potential moderators more thoroughly, as there may be several interaction effects between student and classroom characteristics, such as "student disability category" × "proportion of students with disabilities within the classroom" and "disability category" × "presence of teaching assistants." Therefore, it is important to conduct the present review in order to explore the impact of potential moderators associated with student and classroom characteristics. The present review, besides being up to date, will conduct an extensive risk of bias assessment of all included studies, and will provide separate meta-analyses for each conceptual outcome (academic achievement, socioemotional development and wellbeing). Furthermore, the authors hope to be able to conduct moderator analyses based on the children's specific disability categories and the specific type of inclusion setting. This may shed further light on the initial differential findings from existing reviews.