The NELAC Institute (TNI) is a 501(c)(3) non-profit organization whose mission is to foster the generation of environmental data of known and documented quality through an open, inclusive, and transparent process that is responsive to the needs of the community. The organization is managed by a Board of Directors and is governed by organizational Bylaws.

TNI's vision is a true national accreditation program, whereby all entities involved in the generation of environmental measurement data within the United States are accredited to one uniform, rigorous, and robust program that has been implemented consistently nationwide and focuses on the technical competence of the entity pursuing accreditation. TNI believes such a program will improve the quality and reliability of environmental data used by federal and state agencies.

To support this mission, TNI operates the following programs:

• Administration and Support
• Consensus Standards Development Program (CSDP)
• National Environmental Field Activities Program (NEFAP)
• National Environmental Laboratory Accreditation Program (NELAP)
• National Environmental Proficiency Testing Program (NEPTP)
• Stationary Source Audit Sample Program (SSASP)