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Visible Learning™
Visible Learning MetaX™
Version 1.4 – Updated February 2026

Mainstreaming / inclusion

Overview

  • Influence: Mainstreaming / inclusion
  • Domain: Classroom
  • Sub-Domain: Class composition effects
  • Potential to Accelerate Student Achievement: Likely to have positive impact
  • Influence Definition: Mainstreaming and inclusion involves students with special needs who are placed in a general education classroom. Inclusion is an approach to teaching that has to be consistently done and thought about by the teacher.

Evidence

  • Number of meta-analyses: 11
  • Number of studies: 416
  • Number of students: 4,838,201
  • Number of effects: 711
  • Weighted mean effect size: 0.54
  • Robustness index: 5

Meta-Analyses

Meta-Analyses
Journal Title Author Article Name Year Published Variable Number of Studies Number of Students Number of Effects Effect Size
Evaluation in Education Kavale & Carlberg Regular versus special class placement for exceptional children 1980 Regular vs. special class placement 50 27,000 50 0.12
Journal of Special Education Wang & Baker Mainstreaming programs: design features and effects 1985 Regular vs. special class placement 6 NA 49 0.44
Dissertation Baker Meta-Analytic Evidence for Noninclusive Educational Practices: Does Educational Research Support Current Practice for Special Needs Students? 1994 Regular vs. special class placement 13 2,532 129 0.08
Educational Leadership Baker, Wang, & Walberg The Effects of Inclusion on Learning 1994 Regular vs. special class placement 6 NA 6 0.20
Conference paper Dixon & Marsh The effect of different educational placements on the multidimensional self-concepts of students with mild disabilities: Preliminary results of a meta-analysis 1997 Regular vs. special class placement 70 NA 70 0.65
Research in Developmental Disabilities Oh-Young & Filler A meta-analysis of the effects of placement on academic and social skill outcome measures of students with disabilities 2015 Mainstreaming 24 NA 93 0.31
Educational Research Review Szumski, Smogorzewska, & Karwowski Academic achievement of students without special educational needs in inclusive classrooms: A meta-analysis 2017 Inclusion on non-special needs students 47 4,800,000 47 0.12
Dissertation Ahmad To include or not to include: A meta-analysis on the effect of inclusion on mathematics for children with and without special needs 2016 Integrated vs special class placement 14 NA 6 0.38
Social Education Zumeta Theory and research in social education 2009 Regular vs. special class placement 9 NA 9 0.09
Journal of the Korean Society for Science Education Kim, Park, Bang, Yoonha, & Yoon A meta-analysis of the effect of inclusive education. 2015 Mainstreaming 161 NA 236 0.88
Review of Educational Research Kramer, Möller, Zimmermann Inclusive Education of Students With General Learning Difficulties: A Meta-Analysis. 2021 Inclusive vs segregated settings 16 8,669 16 0.35
TOTAL/AVERAGE 416 4,838,201 711 0.33
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