Why do some organizations adopt new information systems while others do not? Why do some face high costs while others do not? Professor Greenstein has been pursuing this stream of research throughout his career, analyzing the factors shaping the costs of acquiring new computing systems and providing econometric approaches to estimating the costs of adapting new systems to unanticipated problems. In his early work on the transition from mainframe computers to client server systems, he argued that co-invention expenses—the cost of adapting to unanticipated problems—play an essential role in adapting new technology to new circumstances. Today, he finds that co-invention expenses continue to influence IT installations, such as electronic medical records.