6. Conclusions and limitations
The relevance that environmental impact management has for any entity is not a new topic; however, the literature concerning large, medium and small businesses reveals significant differences in performance. The relevance of productive resource constraints and opportunity costs that the development of these practices entails has been one of the most common arguments provided to explain the reduced commitment of SMEs. In this BEZ235 sense, the results of this paper not only fail to confirm these arguments but also contradict them by providing causal evidence that the development of environmentally friendly practices contributes to significantly increased competitive performance in SMEs.