This paper is limited to a comparative study of law and legal systems in contemporary Pakistan and Afghanistan, with an emphasis on how these states approach the complex relationships between Islamic law, tribal customary law, and statutory legal codes. Afghanistan and Pakistan provide valuable comparisons because both states are Muslim-majority countries that are extremely heterogeneous, yet bear the marks of increasingly centralized governments seeking to homogenize national judicial systems amidst rapidly-increasing economic and legal globalization. What is the nature of interaction between Islamic law, local customary/tribal law, and official state-sponsored law in these two countries? Is interaction between these three broad categories of law characteristic of an irreconcilable clash, harmonious fusion, or a series of overlapping jurisdictions? In an age of increasing statutory codification is there a dwindling role for local social customs in the production of Islamic law? How do Afghanistan and Pakistan govern conflicts between Islamic law and local sociocultural norms in tribally-governed areas, or between these bodies of law and international human rights law? By raising the above issues for discussion it is hoped this study will promote more constructive dialogues between international development organizations and local sociolegal actors in heterogeneous societies like Afghanistan and Pakistan, with potential lessons for additional contexts of legal pluralism.