NCSL, founded in 1975, represents the legislatures in the states, territories and commonwealths of the U.S. Its mission is to advance the effectiveness, independence and integrity of legislatures and to foster interstate cooperation and facilitate the exchange of information among legislatures.

NCSL also represents legislatures in dealing with the federal government, especially in support of state sovereignty and state flexibility and protection from unfunded federal mandates and unwarranted federal preemption. The conference promotes cooperation between state legislatures in the U.S. and those in other countries.