Inclusive Education has been part of the international political agenda since the beginning of the ‘90s (UNESCO, 1994). The project of an inclusive school, or a school for all, expects policymakers and practitioners to strive for the common aim of creating educational institutions where all pupils and students learn alongside, independently from their individual functioning, their socio-cultural, linguistic, ethnical or economic background (UNESCO, 2000).

Inclusion and exclusion(s) are considered as two sides of the same coin, none of them can be successful when the other one is not taken into account.

Actions towards inclusion are part of a long and never ending process, regarding all pupils and students in favor of their presence, participation and learning. Likewise, inclusive processes should identify and remove barriers, reduce or eliminate any form of oppression or discrimination that could slow down or hinder the process, producing marginalization, exclusion and underachievement (IBE-UNESCO, 2016). For this reason, an emphasis on cultural, social and institutional change, as well as one on at risk groups are required.

In 2006 the UN Convention for the Rights of People with Disabilities reaffirms the need to take into account the rights of all pupils and students with disabilities, guaranteeing their access to and participation in inclusive school systems. Suitable contextual adaptations and reasonable accomodations are, thus, required to respond to the needs deriving from disabilities (UN, 2006).

Although almost three decades engaged most countries in implementing the ideal of inclusion in the practice, research in the field seems to be still insufficient and does not adequately support the project in terms of positive outcomes. As a consequence, the debate between full inclusionists and opponents is still heated (e.g.  Farrell, 2012; Gordon, 2013; Imray & Colley, 2017).

In particular, researches should provide supportive results in terms of positive effects of inclusion, both on pupils with and without Special Educational Needs. Even if Special Educational Needs is a controversial macro-category (Vehmas, 2010), as it associates all pupils considered “at risks”, such as pupils with disability, difficulties and disadvantages (OECD, 2004), we considered it a useful category to refer to in order to analyse and discuss the effects of school inclusion on pupils and students.

The effects of inclusion on individuals should constitute a pivotal issue when considering implementing inclusion, in terms of academic achievement, participation and socialization but also regarding psychological aspects such as self-concept. Researches about effects of inclusion can use standardized tests, questionnaires, observations or interviews and, consequently, collect data about measured or perceived effects.

Most researches regarding this topic focus on the effects on students with disabilities, often considering specific categories of disability, such as for example Autistic Spectrum Disorders (e.g. Amber, Eidels, & Gregory, 2015; Ashburner, Ziviani, & Roger, 2010).

Few studies focus, instead, on pupils without Special Educational Needs (Kalambouka, et al. 2007) or consider both categories, with and without SEN in parallel (Ruijs & Peetsma, 2009).

Moreover, the lack of systematic reviews available in the field create a debate which is mostly dominated by different ideological positions and individual or group’s perceptions and much less based on empirical data.

Therefore, there is a need to understand if the debate regarding inclusion can be clarified by empirical studies and whether different positionings are supported by the results available.

The review here presented is part of a larger systematic review on measured and perceived effects of school inclusion on all pupils, both with and without SEN, in terms of achievement, participation, social skills and psychological aspects (i.e. attitudes and self-concept).
This abstract is focused on one part of this research synthesis, the systematic review of the literature regarding the effects of inclusion on pupils without SEN.

A systematic review is a literature review whose main aim is to synthesize the research findings in the literature available on a specific topic. This method is useful to inform policymakers and professional about data and evidence available (Cooper, Hedges, & Valentine, 2009). Two main research questions guided the review process: - Does inclusion have effects on the academic achievement of pupils and students without SEN in all school grades and university? - Does inclusion change classmates' effects regarding perceived social skills, self-concept, and attitudes? First of all, a definition of inclusion was chosen as a reference concept for this study. We did not want to apply too specific criteria regarding school and class organization, as we know that the concept is implemented in many different ways across different countries. We chose to consider a broad definition of inclusion, that is of a school for all where the political and institutional attempt is to make all students learn together, under similar circumstances. Some criteria of inclusion and exclusion were initially defined: - General context: Studies conducted in a context of inclusion in any countries from pre-school to University. - Time window: Articles published on international journals, in English, from 2008. The divide is the UN Convention for the Rights of People with Disabilities, in particular considering the last 10 years. - Type of sources: Peer reviewed international journals published in English. - Type of researches selected: Qualitative, Quantitative or Mixed Methods, with clear research procedure and structure. To answer the first question on the effects on academic achievement the studies need to use experimental or correlational designs. To answer the second question on perceived effects, the studies need to use quantitative, qualitative, or mixed-methods designs controlling for methodological qualities and potential bias. The authors are conducting a comprehensive search to locate relevant research. Different electronic databases are consulted (JSTOR, ERIC, PsychINFO, EBSCO) using different combinations of keywords (e.g. "inclusion" "inclusion of pupils with disability / SEN / emotional problems / behavior problems" "peers/classmates" "typically developing peers/classmates" "pupils/students without disabilities / SEN / label / statement" "achievement/performance" "perceived effects" "social skills" "attitudes" "acceptance/rejection" "socio-emotional effects"). References from previous reviews on inclusion and studies found were also investigated.

The results of this systematic review could provide information, on one side, about the influence that inclusive processes have on the academic learning, social skills and attitudes of pupils without SEN and, on the other, regarding the way they experience school inclusion. Three categories of results should emerge: positive effects, negative effects and irrelevant/not significant effects. Quantitative studies will be classified on the basis of the effect size (positive or negative) or the statistical significance of this values. For qualitative research, instead, a set of criteria must be defined to evaluate the division within the three categories. Due to the large amount of the literature available in the field, delimiting criteria of inclusion and exclusion was necessary to make the study feasible. This could of course constitute a limitation of the study and could lead to selection and publication bias, as it excludes from the analysis information deriving from unpublished works, publications in other languages, publications on books and not peer reviewed journals. Similarly, the time limitation leaves out interesting studies published in the previous year. Considering a broad concept of inclusion as a reference, the effects on classmates could be the results of multiple and differentiated causes, related to the quality of the inclusive system itself. Given the complexity of school systems, we must select those recurring elements emerging from the analysis to understand whether some areas of individual functioning are more affected, both positively or negatively, by school inclusion. These outcomes could help identify the shortages of knowledge regarding the effects of inclusion and, moreover, underline those aspects that need to be further or better investigated in relation to their causes.

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