Purpose: The purpose of this paper is to investigate the influence of the accreditation path toward legitimacy in business schools from an isomorphic and a social responsibility perspective. Design/methodology/approach: A qualitative method is used to analyze the Association to Advance Collegiate Schools of Business (AACSB) accreditation process in three Lebanese business schools aiming at revealing a new role of corporate social responsibility (CSR) in this process. Findings: Accreditation in business schools is a "temporary isomorphic legitimacy tool" enhanced by CSR in a continuum that may lead to sustain legitimacy in higher education once accreditation is attained. Research limitations/implications: This research has its limitations around the external validity of the qualitative methods. In fact, the authors' results depend on the context of the three studied business schools, and the generalization of the results was never the authors' primary objective. Further research must be done to build and elaborate on the authors' findings, either within the authors' sample or within other business schools in Lebanon. Practical implications: Corporate social responsibility (CSR) can play a major role in guaranteeing and sustaining legitimacy in the phase after accreditation. May be this was the philosophy behind the proposition of the AACSB of the new standard regarding CSR in 2013 highlighting the importance of ethics, CSR, and sustainability education in business schools. Originality/value: Accreditation in business schools is a "temporary isomorphic legitimacy tool" enhanced by CSR in a continuum that may lead to sustain legitimacy in higher education once accreditation is attained.