This chapter differentiates between abstract legal pluralism and folk legal pluralism. Abstract concepts of law within legal pluralist literature can be placed in one of two broad categories based on form and function: the inner ordering of associations or institutionalized rule systems. However, both types of concepts of law inevitably result in over-inclusiveness by encompassing social phenomena that are usually not considered to be law, creating irresolvable problems. Folk legal pluralism identifies coexisting forms of law in terms of what people collectively view as law, examined through a social-historical lens that pays attention to how forms of law vary across social contexts and change over time. It also articulates three categories of law applied throughout this book: community law, regime law, and cross-polity law. This approach offers a commonsensical account of law and legal pluralism useful for scholars, development practitioners, social scientists, and legal theorists.