Operational psychologists provide a variety of psychological services in support of national security, national defense, and public safety. Their work may include the assessment of personnel for high-risk positions, consultation to investigations and crisis negotiations, support to military or intelligence training and operations, or other types of psychological and behavioral assessments. The practice of operational psychology differs in important ways from other practice areas and has developed significantly over the past 20 years. Given developments in the field, debate about the proper roles of psychologists in national security settings, and psychologists' ongoing need for guidance, these Professional Practice Guidelines for Operational Psychology are provided to benefit operational psychologists, the recipients of their services, and other affected parties. (PsycInfo Database Record (c) 2025 APA, all rights reserved).