The importance of building effective legal and regulatory systems has long been recognized by development professionals, yet there have been few programmatic initiatives that have translated empirical evidence and political intention into sustained policy success. Justice sector reforms have frequently been based on institutional transplants, wherein 'successful� legal codes (constitutions, contract law, etc.) and institutions (courts, legal services organizations, etc.) of developed countries have been imported almost verbatim into developing countries, without thought of the country�s social and cultural situation. Further, the fact that most developing countries have customary legal systems is often overlooked by development practitioners. Many governments, however, have tried to engage with customary systems in one way or another, with differing results. This paper brings customary systems into central focus in the ongoing debate about legal and regulatory reform. It analyses the ongoing challenges and critiques of customary legal systems and examines why, despite these challenges, engaging with such systems is crucial to successful reform processes. It examines the ways customary systems have developed in three African Countries?Tanzania, Rwanda and South Africa?and draws out some of the lessons of these experiences and the implications they have for policy reform initiatives.