This chapter explores policy analysis in trade unions and reveals three factors that play a key role in explaining the type and intensity of the policy analysis activities trade unions develop: the trade unions’ role in the policy process, the trade unions’ organisational characteristics and industrial relations institutions. The analysis shows an erosion of the forms of institutionalised involvement and intermittent patterns of policy concertation that have reduced the trade unions’ participation in public policy making and implementation, especially during the 2008 financial crisis. Before this erosion, the trade unions tried to strengthen their policy analysis capacities, including through the production of evidence-based reports for policy making and more intense use of social networks to reach broader segments of the population, among others. Moreover, they have forged alliances at the EU level in recent years to create and strengthen their research dimension.