Community gardens run from 5'x5' plots to as much as 25' square plots. Usual sizes are in the 10 x 10 to 15 x 15' range. Community gardens are often run by a self-governing set of bylaws, some elect boards in a democratic fashion while others can be run by appointed officials. Most are run by a non-profit, either a community gardening association or a church or other land-owner, and sometimes by a city's recreation or parks department or a school or University. There are many different governing models to choose from. The American Community Gardening Association, has information on starting your own community garden and is a wealth of further information on the subject.