U.S. corporations have long tried to enact a favorable business environment via political activities such as lobbying and campaign contributions. This particular strategy is receiving increased attention due to the recent Supreme Court decision, Citizens United v. Federal Election Commission, which establishes that corporations have the same rights with regard to political activities as individuals. In this work, we examine the nature of corporate political activity and the need for accountability; define transparency in the context of corporate political activity; and examine the antecedents for corporate political disclosure. We then test our model on the S&P 100 using an index of corporate political disclosure that we developed. We find that opportunities to participate in political activities, dependence on government contracts and prior disclosure on other topics such as the environment lead to more disclosure. The intensity of the regulatory environment appears to have no influence.