The preparation of a statement of purpose, scope, and objectives (PSO) is essential to ensure that process hazard analysis studies are focused and complete. A PSO statement defines what must be addressed but also constrains studies to appropriate content. PSO statements help to ensure studies are conducted effectively and efficiently. This article describes the content of a PSO statement and provides guidance on its preparation and use. (c) 2014 American Institute of Chemical Engineers Process Saf Prog 34: 84-88, 2015