Prior literature noted the potential that advanced environmental management might have in the generation of valuable organizational capabilities regarding costs minimization. More-over, during last years, one of the most important objectives in the development of transport public policies has been the internalization of environmental costs. Thus, this study attempts, firstly, to analyze how transport companies could successfully face the challenge of internalis-ing environmental costs, and second, to highlight how the existence of an environmentally proactive pattern of behaviour might reduce the environmental costs on transport sector. In doing so, a case study in the Spanish industry of road freight transport has been elaborated. Despite nowadays companies face the environmental challenge not beyond legal require-ments, the main conclusion of this study is that an environmentally proactive behaviour re-inforces the sustainable development of companies.