Summary: Pursuant to a congressional request, GAO provided information on: (1) the mission, staffing, and operations of the National Association of Insurance Commissioners' (NAIC) Non-Admitted Insurers Information Office (NAIIO); (2) the characteristics of NAIIO approved, unlicensed non-U.S. insurers and state insurance regulators' use of NAIIO screening services; and (3) states' reliance on NAIIO services. GAO found that: (1) the primary mission of NAIIO is to screen unlicensed non-U.S. insurers operating in the United States and maintain a listing of approved insurers; (2) NAIIO depends on NAIC officials to contribute to NAIIO staffing needs; (3) the NAIIO listing operation involves evaluating unlicensed non-U.S. insurers' listing applications and monitoring listed insurers' continued compliance with NAIIO listing criteria; (4) of the 77 non-U.S. insurers listed with NAIIO, 20 are classified as secure, 32 are classified as adequate, and 16 are considered vulnerable to adverse economic and underwriting conditions; (5) NAIC has characterized the insurers listed with NAIIO among the best unlicensed non-U.S. insurers currently operating in the United States; (6) few states rely on the NAIIO listing to screen unlicensed non-U.S. insurers; and (7) states generally use the NAIIO listing at their discretion to determine the eligibility of unlicensed non-U.S. insurers seeking to operate in their state.