Europeanization research dealing with the environmental transition in Eastern Europe has focused on the roles of state actors in adopting European regulations. Less well understood are the framings and roles of public administration actors when European Union regulations do not prescribe specific institutional changes. This article offers a micro perspective on the framings and roles of such actors in several cases of brownfield regeneration. Actors can play a proactive role, thereby fostering change, or they can play a moderately active or a passive role. We identify three moments—defining brownfield problems, mobilizing networks, and leading by example—which together define an entrepreneurial path. Along this path, actors can evolve from passivity toward entrepreneurship, but stasis and regression are also possible. Using qualitative data from the project TIMBRE (Tailored Improvement of Brownfield Regeneration in Europe), we illustrate different moments along this path for public sector actors in the Czech Republic, Poland, and Romania.