Systems Service Enterprises, Inc. (SSE) is a leader in Information Technology, Cybersecurity Compliance, and Training and Technical Data solutions for small-medium sized businesses and specializing in Department of Defense (DoD) contracting. A Women-Owned Small Business (WOSB) with 150 employees, SSE was founded in 1966 by Susan S. Elliott. SSE is headquartered in St. Louis, MO and is able to serve clients throughout all 50 states. As an ISO 9001:2015 certified organization, SSE has not only the technical expertise, but the disciplined processes and business maturity to deliver customized best-in-class IT and cybersecurity solutions across several highly regulated industries. As a DoD contractor itself, SSE has maintained our and our customers’ networks to evolving regulatory standards and protects data for ourselves and our clients. In November of 2024, SSE successfully completed a Joint Surveillance Assessment with a C3PAO and DIBCAC, achieving a perfect score of 110 for its CMMC Level 2 Certification. Established processes, standards and quality solutions allow SSE to meet the most complex challenges for our clients…both now with respect to NIST 800-171, as well as looking ahead to plan for future needs including CMMC.
Looking for a particular SSE employee's phone or email?
The SSE annual revenue was $49.4 million in 2026.
Elizabeth Niedringhaus is the President and CEO of SSE.
380 people are employed at SSE.
SSE is based in St. Louis, Missouri.
The NAICS codes for SSE are [51, 5191, 54, 541, 519, 51919, 519190].
The SIC codes for SSE are [737, 73].