This lecture provides a general framework for analysing unemployment. For inflation to be stable, there must be sufficient unemployment to prevent ''target real wages'' exceeding ''feasible real wages''. Target real wages depend on bargaining systems, benefit systems, labour market policies and mismatch. This framework explains inter-country differences in unemployment rates and British time series. The Restart Programme has helped in a major way to reduce British unemployment. Long-term unemployment is an almost total economic waste since it does little to reduce target real wages. It also imposes major external costs on British taxpayers since long-term unemployed people are so unlikely to become re-employed. Britain should adopt the Swed...