Environmental innovation (EI) plays an important role in decoupling economic growth and environmental harm. This paper focuses on the environmental innovation behavior of companies in transition countries of Eastern Europe and Central Asia, which have been little studied so far. These countries share the Soviet legacy of environmental mismanagement, and have restructured their innovation systems relatively recently in the course of transition. The EBRD-EIB-WB Enterprise Survey (2018-2020) allows us to examine the determinants of environmental innovation in 29 transition countries. Although the theory places a greater emphasis on external sources of knowledge in EI, the results indicate that collaborative R&D is still quite weak in these cou...