Local energy transitions involve various types of actors (e.g., politicians, businesses, public administrators, and citizens) that differ in their objectives, values, problem-related perspectives, and professional jargons: these differences risk deterring the collaboration that is needed to pursue energy transitions as encompassing socio-technological transformations. Based on a boundary work-approach, this contribution studies the interplay of actors in these transitions. The approach suggests that boundary bridging arrangements (e.g., boundary objects, boundary settings, and boundary organizations) evolve in local energy transitions, facilitating communication across the boundaries between the various types of actors. In applying the boundary work approach to the energy transitions in two German cities, the article explores the potentials and limitations of this approach.