This special issue is the outgrowth of a 2007 conference, Entrepreneurship: Strategy and Structure, sponsored by the NBER Working Groups on Entrepreneurship and Innovation Policy and the Economy. The aim of the conference and special issue are to provide a forum for rigorous frontier research on the microeconomic and institutional foundations of entrepreneurship, and the strategic and market consequences of entrepreneurial activity. The papers included in the Special Issue include a subset of papers presented at the conference as well as papers submitted as the result of a solicitation for the Special Issue from the journal. As with all special issues in JEMS, all of the articles in this issue have gone through the standard editing and refereeing process that is applied to all submissions to JEMS. We would especially like to thank Dan Spulber, Josh Lerner, and Bob Strom for their help throughout the process, and the Kauffman Foundation for providing support for the original NBER conference.