Since 2010, the Federal Government has committed substantial funds to promote adoption of electronic health records (EHRs). Early policies to promote adoption assumed that a competitive market of vendors would emerge to meet the new demand for EHRs created by the policy. But recent data shows that three large vendors dominate the market, while a very large number of vendors serve only a tiny proportion of providers. This pattern likely limits meaningful EHR use and health information exchange. Anecdotally, it is difficult for providers to evaluate the quality of products before purchase, and significant barriers prevent them from switching vendors when dissatisfied. Yet there is still little systematic research that can inform attempts to shape health IT markets. Our project will explore ways in which the structure of health IT markets and related government policies affect healthcare practice and management, integrating analysis of relevant markets, regulations, and practice.