Using a two-country model of endogenous growth with international knowledge spillovers, this study analyzes the welfare consequences of global corporate income tax competition. Although the Nash equilibrium tax rate can be excessively high or low according to the degree of spillover, this does not lead to significant welfare losses. The key to this outcome is that corporate income tax competition for growth maximization, which we consider hypothetically, attains the maximum growth rate despite complex externalities and strategic interactions.