The relationships between the difficulty of entry and competitive strategies in five industries, chosen for their differing structural contexts, were tested. Statistical support was found for the value of pre-entry analysis of entry barriers and of firms' predicted responses to potential entry. In particular, the creation of idle productive capacity appears to be a potent deterrent to new entrants.* This research was undertaken while on the faculty of The University of Texas at Dallas. The author wishes to acknowledge Muhammed Daud for programming assistance, and thank the anonymous reviewers and Richard Bettis for helpful comments and suggestions. None but the author should be held responsible for remaining errors.