This paper aims to assess the degree of comprehensiveness of corporate social responsibility (CSR) reports of Brazilian companies and its determinants. Literature suggests that a report is considered comprehensive when it contains three types of information for each CSR item published: vision and objectives; management actions; and performance indicators. A content analysis of 272 CSR reports of Brazilian companies that follow the Global Reporting Initiative (GRI) guidelines was conducted for the period from 2010 to 2013. Results indicate that, despite the still low coverage of contents in CSR reports, there has been an increase in the degree of comprehensiveness over the period of study. Some firm attributes affect the comprehensiveness degree of CSR reports: ownership concentration in hands of the main shareholder; company presence in the ISE (Corporate Brazilian Sustainability Index); the environmental risk of firm industry; firm size and profitability.