This paper reviews domestic and multinational corporate tax research. For each topic, the theoretical arguments explaining how taxes can affect corporate decision-making and firm value are reviewed, followed by a summary of the related empirical evidence and a discussion of unresolved issues. Tax research generally supports the hypothesis that high-tax rate firms pursue policies that provide tax benefits. Many issues remain unresolved, however, including understanding whether tax effects are of first-order importance, why firms do not pursue tax benefits more aggressively, and whether corporate actions are affected by investor-level taxes. © 2006 J.R. Graham.