Archival research suggests that nonprofit organizations are inaccurately reporting significant asset diversions on IRS Form 990. This suggests that information reported on Form 990, which is relied on by nonprofit stakeholders, may be misleading. As a result, this behavioral study investigates three possible causes for the under-reporting of significant diversions of assets, including reading the Form 990 instructions, how the threshold for reporting is met, and the threat of outside detection of the theft. Our findings suggest that reading the instructions for Form 990, where the IRS’s definition of a significant diversion of assets can be found, positively and significantly influences disclosure of an asset diversion. We also examine press release reporting of a significant diversion of assets, as nonprofits may try to get ahead of the disclosure on Form 990. We find that risk of detection of the theft is a significant predictor of press release disclosure.