This paper investigates whether the ethical or opportunistic motives of CSR dominate managers' actual behavior in their choice of disclosure complexity and language in the annual report. Using a large US sample from 1999 to 2013, we find that firms with high CSR orientation provide more readable disclosures and use less ambiguous tone in their annual reports. These findings are consistent with the notion that managers in CSR-conscious firms adhere to high ethical standards and commit to improving the transparency of their firms' financial disclosures. We also show that CSR orientation affects investor perception of corporate disclosures. In particular, CSR investments serve as a channel to mitigate the adverse impact of less readable / more ambiguous tone on stock price volatility around the filing of 10-K reports. Our results are robust to alternative measures of readability and CSR orientation, sampling method, and potential endogeneity.