For almost twenty years, Brookings Papers on Economic Activity (BPEA) has provided academic and business economists, government officials, and members of the financial and business communities with timely research of current economic issues. Contents Include: Articles: RICHARD E. CAVES, MICHAEL D. WHINSTON, and MARK A. HURWITZ Patent Expiration, Entry, and Competition in the U.S. Pharmaceutical Industry FRED MANNERING AND CLIFFORD WINSTON Brand Loyalty and the Decline of American Automobile Firms STEVE J. DAVIS and JOHN HALTIWANGER Wage Dispersion between and within U.S. Manufacturing Plants, 1963-86 FRANKLIN M. FISHER Organizing Industrial Organization: Reflections on the Handbook of Industrial Organization ALVIN K. KLEVORICK Directions and Trends in Industrial Organization: A Review Essay on the Handbook of Industrial Organization ROBERT D. WILLIG Merger Analysis, Industrial Organization Theory, and Merger Guidelines