In response to a growing public demand for corporate accountability and social responsibility, large companies are investing increasing efforts in the communication of their responsible conduct. Through corporate social reports, they voluntarily account for the social and environmental effects of their operations and document their efforts to implement sustainability principles. This paper presents a comparative analysis of BP’s and IKEA’s 2009 corporate social reports. The analysis combines Appraisal theory and corpus-linguistic methods to identify and compare patterns of evaluative language and modality in the two reports. The main goal of the analysis is to explore how, through these language resources, BP and IKEA construct their corporate identity and negotiate their relationship with their audience. The analysis reveals significant differences in the use of Appraisal resources between the two reports, which reflect broader differences in the relative emphasis the companies put on certain traits of their corporate persona.