The objective of this article is to provide an account of the activation turn that has taken place in most OECD countries over the last two decades. Taking a political science perspective, this article puts forward a number of explanations that help us understand why this happened. It argues that three factors are particularly helpful in order to account for this shift：the development of post-industrial labour markets in OECD economies; the failure of alternative approaches to mass unemployment and the wish of political parties to claim credit for innovative and modern labour market reforms. This argument is illustrated by the trajectories followed in seven European countries： Denmark, the UK, the Netherlands, Sweden, Germany, France and Italy.