Public institutions and trade unions in particular are often portrayed as facing a deep crisis. In order to better understand to what extent unions are still perceived as legitimate institutions from the society as a whole (working and non‐working individuals), we analyse the determinants of confidence in unions across 14 European countries between 1981 and 2009. Confidence in unions is explained through individual‐level variables (by a rational and an ideational mechanism) and contextual‐level factors (relevant economic and employment relations characteristics). Using data from the European Values Study (EVS) merged with contextual datasets, we develop a series of regression models to examine the main determinants of confidence in unions. We demonstrate that confidence in unions cannot only be traced back to the support from members and left‐wing oriented individuals but it is also related to non‐working individuals and vulnerable social groups, in particular when confronted with economic shocks. Our findings challenge both the ‘crisis of confidence’ in institutions and the ‘crisis of unionism’ narratives. Implications for union representation and organizing strategies are discussed.