The objective of this paper is to explore how the various stages of consciousness development of top managers can influence, in practical terms, their abilities in and commitment to environmental leadership in different types of SMEs. A case study based on 63 interviews carried out in 15 industrial SMEs showed that the organizations that displayed the most environmental management practices were mostly run by managers at a post-conventional stage of consciousness development. Conversely, the SMEs that displayed less sustainable environmental management (...) practices were all run by managers at conventional stages of development. Drawing upon diverse examples of environmental leadership, this paper analyzes the reasons why the stages of post-conventional consciousness development of top managers seem to foster corporate greening in SMEs. The study also sheds light on the key values and abilities associated with both environmental leadership and the upper-stages of consciousness development, which include a broader and systemic perspective, long-range focus, integration of conflicting goals, collaboration with stakeholders, complexity management, collaborative learning, among others. (shrink)