CSR and corporate sustainability have long been seen as a way for companies to strengthen legitimacy and competitiveness. However, there is conceptual confusion about CSR and sustainability, how the concepts are defined, used and operationalized within companies. The purpose of the thesis is to investigate how the concepts of CSR and sustainability are understood and operationalized by Swedish companies in their sustainability reports, and whether the concepts are used as interchangeable. The study is carried out on the basis of a qualitative content analysis of sustainability reports. Theories in CSR, sustainability and sensemaking, as well as previous research on the interchangeability of the concepts are used to analyze and discuss the results of the content analysis. The study thus contributes to an increased understanding of the meaning of the concepts and how they create meaning in an organizational perspective. Something that affects how information products, in this case sustainability reports, are both written and perceived by its readers. The results of the study show that the concepts, despite different historical backgrounds, have converged. Companies understand and operationalize CSR as the social dimension of corporate sustainability, and in some cases use the concepts as synonyms as a way to reach the company´s strategic goals and advance sustainable development. Companies thus construct their own interpretations with the aim of making the concepts meaningful to the organization.