The interpretation that decision makers have in companies about the concept of Corp orate Social Responsibility (CSR) is a critical factor for their incorporation into business practice. From this interpretation depends the degree of transversality with which it is applied and the way it is managed. Given the importance of the subject, an investigation was carried out aimed at identifying the ways in which decision makers in SME companies (directors, managers and middle managers) define CSR. First, a typology of definitions on CSR was built based on the analysis of documents produced by academics and institutional actors during the last 50 years. Then, an intentional sample of decision makers in SME companies was selected and an interview guide was applied based on open questions, whose answers were later analyzed by qualitative and quantitative techniques. It was found that the five definitions identified in the literature are present in the sample studied, but predominantly the three that define CSR as: contribution of the company to the solution of social problems, incorporation of the expectations and demands of the stakeholders and responsible management of the externalities of the operation.