This thesis explores two subjects: corporate social responsibility (CSR) and social responsibility disclosure (SRD). Its primary aim is to extend knowledge of SRD in Portugal. A multi-theoretical framework for the analysis of SRD, which combines resource-based perspectives (RBP) and social and political theories, is developed. According to the theoretical framework adopted, the contribution which CSR and SRD may have to financial performance is nowadays primarily related to qualitative factors, such as employee morale or corporate reputation. This investigation of SRD in Portugal analyses the nature of SRD in annual reports and on the Internet by a sample of companies listed on Euronext – Lisbon, and by a sample of Portuguese banks. It also examines the use of the Internet for SRD by the best companies to work for in Portugal (as assessed by the Great Place to Work Institute Portugal) compared to a group of matched companies. Using content analysis, SRD was classified in terms of theme (environment, human resources, products and customers and community involvement). Results suggest that the framework adopted may be useful in the analysis of SRD and should be further developed and used. At the theoretical level, this thesis develops a framework for analysis of social responsibility activities and disclosure by exploring the usefulness of RBP in understanding the motivations companies have to engage in these practices. At the empirical level, an important contribution is made to the knowledge of SRD practices in Portugal by providing new empirical data. In addition, this thesis addresses some shortcomings in SRD research. First, the limited emphasis on the impact of CSR related to human resources and the possible effects which SRD may have on such impact. Second, the scantiness of studies on social responsibility and disclosure practices of companies belonging to sectors with little environmental impact, such as banking and finance. Another aspect which this thesis addresses pertains to the analysis of other disclosure media besides annual reports, in particular the Internet. By analysing both these two media this thesis contributes to the scarce literature analysing more than one medium of SRD.