One of the most contentious issues raised during the recent crisis has been the potentially exacerbating role played by mark-to-market accounting. Many have proposed the use of historical cost accounting, promoting its ability to avoid the amplification of systemic risk. We caution against focusing on the accounting rule in isolation, and instead emphasize the interaction between accounting and the regulatory framework. First, historical cost accounting, through incentives that arise via interactions with complex capital adequacy regulation, does generate market distortions of its own. Second, while mark-to-market accounting may indeed generate fire sales during a crisis, forward-looking institutions that rationally internalize the probabil...