Complementary Currency Systems (CCS) are accounting systems that define local monetary spaces created by non-bank actors to pay for exchange of goods and services inside a trading network. This article aims to investigate the capability of complementary currency systems to foster social and economic changes. The authors use an analysis of the literature to examine the nature and diversity of CCS in terms of objectives, forms, modes of governance, and degrees of connection with political authorities and economic structures. They also assess the potential of CCS to support local economies based on social and environmental values, working to combat economic vulnerability and social exclusion, and examine how CCS challenge the conventional perception of money. The article ends by summarizing the challenges facing CCS, inquiring into the potential problems and benefits that a change of this sort could entail.