This article reflects on the current state of the dynamically growing research and practice related to sustainable business models (SBMs), motivated by the question of whether dealing with SBMs is just a passing fancy or an emerging field, maybe even a field in its own right. We follow Ehrenfeld (2004), who asked a similar question for the field of industrial ecology in this journal, and reflect on the major beliefs and concepts underpinning SBM research and practice, tools and resources, authorities and the related community of actors. These elements are considered characteristics of a field and must be institutionalised in academia, industry and government for a field to emerge and progress. We therefore also identify some institutionalisation tendencies. As a result, we conclude that SBM research and practice show traits of an emerging field. It is however too early to foresee if it will develop as a sub-field within already established domains ("sub-field hypothesis") or as a stand-alone field ("stand-alone hypothesis"). We argue that the sub-field and the stand-alone positioning may hamper the unfolding of the field's full potential. Instead, we propose that the SBM field needs to assume the role of an integrative field to break existing academic niches and silos and maximise practical impact ("integration hypothesis"). Our observations indicate that the SBM field is indeed developing into an integrative field and force. But we need to better understand and strengthen this development, for example by crafting a dedicated SBM research programme. A series of critical reviews could be a starting point for such an endeavour.