The goal of Subsurface Containment Assurance is to ensure that no environmental damage, damage to operated assets, or impacts on well operations (drilling or production) are incurred by leakage of production or injection fluids from their intended zones. Subsurface Containment Assurance involves the integrated efforts of the subsurface (reservoir and overburden characterization), the wells (planning, construction, well integrity and abandonment) and the operations (process and well operations and management of change) teams. Disciplines must act together to develop and implement a surveillance plan to proactively monitor containment during well and injection operations. The paper will describe the elements of a Subsurface Containment Assurance Program that are required for business units operating across the entire life cycle from exploration to mature developments. The program is designed to be comprehensive yet flexible, and focuses on the critical elements and risks for individual operating units. A consistent framework has been created and implemented that draws from existing tools for reservoir and overburden characterization and field management, and combines these tools to reduce the risk of unintended subsurface fluid containment loss. Specific assessment criteria and ranking approaches and tools for qualitative and quantitative estimation of containment risks will be reviewed. Lastly, practices for deepwater subsurface containment and implications for the oil and gas industry will be discussed.