In the U.S., a form of financing that can be used by cities, counties and special districts (such as school districts) to finance major improvements and services within the particular district. Special taxes and bonds used for Mello-Roos financing can only be issued by counties or districts in which two-thirds of the voters in the area have voted in favor of becoming a Mello-Roos district. 

|||Mello-Roos districts may issue municipal bonds to finance development projects with high costs. If voters in the area have elected to become a Mello-Roos district, they are responsible for the repayment of these bonds through a special tax, assessed annually based on the value of the properties within the district. Mello-Roos financed developments might include schools, roads, libraries, police and fire protection services or ambulance services. This type of financing is named after Henry Mello and Mike Roos of the California legislature, who sponsored legislation in 1982 to authorize this form of financing.