In this article, we review and assess research on the role of trade unions in labour markets and society, the current decline of unions and union revitalisation. The review shows three main trends. First, trade unions are converging into similar strategies of revitalisation. The ‘organising model’ has spread far beyond the Anglo-Saxon countries and is now commonplace for unions as a way to reach new worker constituencies. Thus, even in ‘institutionally secure’ countries like Germany and the Nordic countries, unions are employing organising strategies while at the same time trying to defend their traditional strongholds of collective bargaining and corporatist policy-making. Second, research has shown that used strategies are not a panacea for success for unions in countries that pearheaded revitalisation. This finding points to the importance of supportive institutional frameworks if unions are to regain power. Third, especially in Anglo-Saxon countries, unions are building external coalitions with other social movements, including across borders, to compensate for the loss of power resources that were tied to national collective bargaining and policy-making. Research has shown that unions, even in adverse institutional contexts, can be effective when they reinvent their repertoires of contention, through political action or campaigning along global value chains.