Building on the argument for a ‘double bottom line’ of financial and social/poverty objectives, some argue for a third bottom line to engage with environmental crises (Hall et al., 2008; Huybrechs et al., 2015). In this chapter, we provide an overview of nascent practices of ‘green microfinance’ and develop a perspective on how (micro) finance relates to the transformation to sustainability. This topic is new on the microfinance research agenda. Garcia-Perez et al. (2017: 3390) report a shallow presence of environmental issues in only 8 percent of microfinance studies, concluding that ‘(t)he environmental dimension features both a very small number of papers and very generic information processing’. As we argue below, this relates to the complex challenging nature of the topic which requires a wide-ranging research approach.