Fostering co-ordinated management of a transboundary basin can benefit from an understanding of the internal, often multilevel governance mechanisms in each country sharing it. This chapter delves into the legal and institutional architecture of water governance in basins shared between Afghanistan and Pakistan. Drawing on a careful document analysis as well as expert interviews, the chapter analyses the national laws and institutions in Afghanistan, as well as the legal and institutional provisions for water governance at the federal, provincial and local levels in Pakistan. A review of the existing design of internal water governance in both Afghanistan and Pakistan reveals that despite the existence of well-meaning and well-structured legal provisions, implementation is a key challenge for effective water governance to be addressed on both sides of the Durand Line. The chapter concludes that strengthening internal institutions for better implementation and engaging multilevel stakeholders for improved co-ordination of water policies between riparian countries can pave the path towards successful transboundary basin management in the Kabul, Kurram and Gomal river basins.