Abstract: This paper examines the design of a federal regulatory structure for insurance companies in the United States, assuming some form of an optional federal charter is adopted. Any design must take account of the objectives of insurance regulation, the convergence of financial service powers among banks, securities, and insurance firms, the types of lines to be regulated at the federal level, and problems posed by the possible participation of nationally chartered insurers in state residual pools and guaranty funds. This paper argues that the creation of a new federal insurance regulator should be accompanied by more consolidation and less fragmentation in the overall federal regulatory structure, by placing the new regulator within an operationally strengthened President's Working Group on Financial Markets. Ideally, a new optional federal charter should provide a real federal option by having the federal government fully regulate the safety and soundness and product lines of all insurers choosing the federal option. However, if lines were to be split between federal and state regulation, safety and soundness regulation of all insurance companies choosing a federal option should take place exclusively at the federal level, leaving the states with responsibility for consumer protection regulation in non-federal lines. While state guaranty funds have functioned effectively overall, a national guaranty fund would have the advantage of uniting responsibility for insurance and safety and soundness regulation, as in the case of banking.