This article studies trade union revitalization within broader trends of projectification that marks a shift towards project work and its temporary organization. It accordingly compares instances of project-based organizational restructuring in post-crisis Estonia and Slovenia in order to identify their drivers, power resources employed and their outcomes and wider impact. In both countries, project-based organizational restructuring was driven by proactive activists capable of innovatively utilizing available power resources and new opportunity structures that had opened up with EU integration. While Slovenian unions utilized a more diverse set of power resources and revitalization strategies, activists in both countries stimulated trade union project-based organizational restructuring in order to initiate and sustain their main, context specific, revitalization strategies. Findings also show that project-based organizational restructuring can be an interim phase for unions to increase their resources and use them to turn their revitalization strategies into more permanent ones.