Over nearly three decades of British rule, mental health illness sparked complex, consequential interactions in Palestine: between colonial state and society, Arabs and Jews, and Palestine and the wider region. The introduction outlines Mandatory Madness’s focus on the social and cultural history of colonial psychiatry in mandate Palestine and argues for its significance across three distinct fields: as offering a novel account of the mandate period, which stresses entanglement rather than assuming division; as shifting the focus in histories of psychiatry away from institutions and experts and towards encounters; and as challenging methodological nationalism by revealing regional and global forms of interconnection. The introduction also reflects on the possibilities and perils of working with the archives of colonial psychiatry in mandate Palestine and provides an overview of the political history of the period to orient readers across the rest of the book.