This chapter describes how OECD countries have incorporated fiscal management issues in their constitutions, studying the regulation of areas such as budget scope and timing, fiscal rules, legislative procedures, and independent fiscal institutions. It highlights how certain provisions can help ensure governments’ adherence to high-level principles of financial prudence, transparency, and accountability. It analyses the potential benefits of enshrining such matters in constitutional terms, such as immutable standards by which the electorate can hold successive governments accountable, lower borrowing costs from reassuring financial markets of commitments to fiscal sustainability, and a more informed legislature to scrutinise fiscal policy. It also assesses the drawbacks, in particular, the fact that they can reduce a government's flexibility to respond to unexpected developments and to adapt the rules to new state-of-the-art practices.