This study adds to the empirical evidence that privatization improves the performance of divested firms and offers preliminary evidence as to why these performance improvements occur. Using a sample of 129 share-issue privatizations from 23 developed (OECD) countries, we first document significant increases in profitability, efficiency, output, and capital expenditure following privatization. Our data indicate that ownership (both private and foreign), degree of economic freedom, and level of capital market development significantly affect post-privatization performance. A comparison to the findings of Boubakri et al. (2005) [Boubakri, N., Cosset, J., Guedmani, O., 2005. Liberalization, corporate governance, and the performance of newly privatized firms. Journal of Corporate Finance (this issue)] suggests that several determinants of post-privatization performance improvements differ between developed and developing countries. (c) 2005 Elsevier B.V All rights reserved.