The aim of this paper is to analyze whether a number of firm and industry characteristics, as well as media exposure, are potential determinants of corporate social responsibility (CSR) disclosure practices by Spanish listed firms. Empirical studies have shown that CSR disclosure activism varies across companies, industries, and time (Gray et al., Accounting, Auditing & Accountability Journal 8(2), 47–77, 1995; Journal of Business Finance & Accounting 28(3/4), 327–356, 2001; Hackston and Milne, Accounting, Auditing & Accountability Journal 9(1), 77–108, 1996; Cormier and Magnan, Journal of International Financial Management and Accounting 1(2), 171–195, 2003; Cormier et al., European Accounting Review 14(1), 3–39, 2005), which is usually justified by reference to several theoretical constructs, such as the legitimacy, stakeholder, and agency theories. Our findings evidence that firms with higher CSR ratings present a statistically significant larger size and a higher media exposure, and belong to more environmentally sensitive industries, as compared to firms with lower CSR ratings. However, neither profitability nor leverage seem to explain differences in CSR disclosure practices between Spanish listed firms. The most influential variable for explaining firms’ variation in CSR ratings is media exposure, followed by size and industry. Therefore, it seems that the legitimacy theory, as captured by those variables related to public or social visibility, is the most relevant theory for explaining CSR disclosure practices of Spanish listed firms.