Inclusive education is a new teaching approach aiming at educating all students in general classrooms and overcoming diversity related to discrimination in education, and has been legally established in many countries in recent years. For its implementation, educators are required to change their beliefs about teaching and their way of practice as well as acquiring new knowledge and skills. Professional development is the method of choice to support educators in this change process. This meta-analytic review aims at investigating the impact of professional development participation on educators’ beliefs, knowledge and skills. Previous reviews have focused on specific aspects addressed in inclusive education as special educational needs or professional development efforts specific geographic areas. The current study aims at expanding previous findings by including a wide range of diversity features, different study designs and addressing the interplay of knowledge, beliefs and skills. Included will be studies using a pre-post-measurement design, control-group-designs and correlational designs, investigating the influence of professional development on employed educators’ beliefs and knowledge about inclusive education and inclusive teaching practices.