How can the path of societal development be redirected towards sustainability? Since recently, the topic of innovation has been moving more and more to the front of the debate. For an evaluation of the problem as to how innovations can be put into the service of sustainability it is first of all crucial to understand the characteristics of the innovative process. This study starts with the reconstruction of recent approaches of innovation research within the fields of (evolutionary) economics and social science. They underline correspondingly the non linear, cross-linked character of innovations and the close relation between technological changes on the one hand and organisational, social as well as institutional changes on the other hand. The next step is the characterisation of non incremental radical innovation and/ or system innovation since they have a special significance in respect to sustainability. Finally, the study ends with reflections on criteria and evaluation methods for sustainability innovations as well as the identification of key questions for further research.