The Software, Simulation, Systems Engineering and Integration Directorate provides collaborative and innovative life cycle systems engineering, software engineering, modeling and simulation, systems development, prototyping, and technical systems management products and solutions. S3I provides mission excellence in all disciplines, staying focused on the customer to enable delivery of solutions to the Warfighter. S3I comprises a highly skilled, credible, and diverse workforce that is responsive to customer requirements: cost, schedule, and performance.

Effective Jan. 19, 2020, the five AvMC directorates were realigned into three. S3I, formerly known as the Systems Simulation, Software and Integration Directorate, remains largely unchanged. The prototype integration facility, along with some other elements that previously fell under the Engineering Directorate, is now realigned under S3I.