In Colorado the only charter authorizer is either the local school or else the state Charter School Institute. However, other states have a variety of authorizers such as the Indianapolis Mayor's Office, colleges and universities, non-profit organizations, and State Boards of Education.
Why different authorizers? For the same reason there is a wide variety of charter schools: innovation. Authorizers that have the sole responsibility of chartering (e.g. the Colorado Charter School Institute) tend to be better at holding their charter schools to high levels of performance.
The primary roles of the authorizer are to 1) decide which charter applications are accepted, and 2) monitoring and oversight. This responsibility to hold a chartered school to a high performance level is done through a performance contract, or charter. Authorizers often wrestle with the desire to let their schools operate autonomously and yet be held to high levels of accountability. This delicate balance is further complicated when the charter schools slips in financial or academic performance.
There is a national organizations for authorizers, called the National Association of Charter School Authorizers (NACSA). Their website is at: www.qualitycharters.org. They have highly regarded quality standards for charter school authorizers and a variety of best practice documents in their resource library. Further, they hold an annual conference with helpful information.