This entry provides a review of the history of developments in library automation in the United States. It discusses four contexts within which library automation should be seen, and does so within each of six time periods: 1) pre-1945; 2) 1945–1960; 3) 1960–1975; 4) 1975–1990; 5) 1990–2008; and (6) post-2008. In each time period, it reviews the societal context and the information technology context, and then two library contexts—technical services and information services.