The Leapfrog (LF) initiative, directed at improving patient safety in hospitals, may be the most ambitious, coordinated attempt to date on the part of large employers to shape the delivery of health care in America. This article assesses the role of market conditions and other factors in influencing hospital responses to LF activities at the community level. Community characteristics were found to be important in explaining hospital participation in a LF safety standards survey at the study sites. However, characteristics of the individual hospitals, and of the LF goals themselves, were more important in explaining the relatively limited progress by hospitals across all sites in achieving those goals over a 5-year period. © 2008 Sage Publications.