The increasing interest in eco-innovation or environmental innovation as a strategy not only to address the serious global environmental problems but also as a source of competitive advantages for companies and for the emergence of new business areas, leads us to try to identify the different factors that act as determinants of its development and adoption at the micro level. In this paper we integrate the findings from several recent empirical studies according to our own classification of factors derived from the variables used in those analyses. From a conventional perspective we referred to the structural characteristics of firms (size, sector, age), the business logic (cost savings, market expansion) or to its technological competence (R&D, path dependencies, qualification of staff and management, cooperation and participation in networks, etc.). We added another category to refer to organizational or marketing innovations that reflect the existence of a certain environmental strategy within the company. In general, the findings show that factors influencing conventional innovation also work in relation to eco-innovation, in particular those related to cost savings and technological competence. Therefore, along with a stringent environmental regulation (justified because of the specific characteristics of eco-innovation) specific supply and demand side instruments are convenient. Measures to disseminate environmental information amongst all stakeholders can also be very useful to promote environmentally friendly and economically viable products and processes, as well as forms of organization and new business.