The American Customer Satisfaction Index (ACSI) is anew type of market-based perform ance measure for firms,industries, econom ic sectors,and national economies.The authors discussed the natureandpurposes of ACSIand explained the theory underlying theACSI model,the nation-wide survey methodology and econometric approach employed to esti mate the indices.The authors concluded with a discussion of the implication of ACSI for public policym akers,managers,consumers,and marketing in general.