This paper examines the impact of entry on the structure of the U.S. chemical industries in the period 1963-1982. The paper measures both the immediate impact of entrants in terms of number, size and market shares and their subsequent growth and/or exit. Particular attention is devoted to the examination of entrant heterogeneity. The paper finds that while a large number of entrants appear in the chemical industries, they have a relatively small long-run impact. In addition, compared to previous work entrants are less important in the chemical industries than in manufacturing sector as a whole. Finally, the post-entry performance of new firms varies significantly across different categories of entry.