This study proposes a theoretical perspective that firms engage in continuous search and selection activities in order to improve their knowledge base and thereby improve their performance. This general framework is applied to the context of corporate evolution. Entry and exit activities are understood as search and selection undertaken by the firm to improve their performance. One of the compelling features of this framework is that firms learn from their past entry experience and approach the next entry in a more focused and directed manner over time. Also, firms acquire additional knowledge from each entry event while applying their existing knowledge base. With a longitudinal (1981-89) data base on entry and exit activities of all publicly traded manufacturing firms in the United States, this study shows that applicability of the film's knowledge base plays an important role in predicting which businesses a firm enters or exits. Firms sequentially enter businesses of similar human resource profiles and firms are more likely to divest lines of business of different profiles. Corporate-level analysis shows that such well-directed entry and exit contribute to the improvement of a firm's profitability.