This guidance document provides an overview of the rationale for and evidence supporting iOAT, as well as guidance on implementation, operation, and evaluation of iOAT programs. Its partner document, National Injectable Opioid Agonist Treatment for Opioid Use Disorder Clinical Guideline provides three key clinical recommendations as well as clinical guidance on the provision of iOAT. The target audience of this document is policy makers, clinical and operational leads in health authorities, team leaders, funders, and organizations that provide substance use disorder and addictions treatment and care.