This paper deals with trends and cycles of unemployment and labour-force participation. Empirical evidence on both trends and cyclical movements in unemployment and participation is presented. Some of the mechanisms behind the observed developments are also analysed, examining how well they fit into different theoretical frameworks. The implications for the assessment of labour market slack of the observed interplay between unemployment and participation are discussed. The paper ends by presenting some unexplained puzzles concerning the interplay between trends and cycles of unemployment and participation ...