Members of the Auxiliary Unit are private citizens who volunteer their time to serve the city by working with the Parks Enforcement Patrol (PEP) branch of the New York City Department of Parks & Recreation.

Auxiliary officers undergo extensive training before going on patrol. Candidates for the Unit must prove their riding skills and learn about PEP policies and procedures, use of radios and Parks rules and regulations before acceptance into the Unit and clearance to patrol.

Mounted patrols ensure the preservation of the natural and living resources in the city's parks, as well as the safety of those utilizing the parks, by maintaining a clearly visible presence. They monitor areas that are not accessible by vehicle; they deter, identify and report illegal or unsafe activities that require PEP or police attention; and they advise the public on park rules and regulations.

Last year, Auxiliary officers assisted dozens of injured park users, providing comfort as well as a physical barrier from oncoming cyclists and rollerbladers, while securing medical assistance in a timely fashion. In addition, they reunited scores of upset and frightened children with distraught parents. Mounted Auxiliary officers also control large crowds at special events like the St. Patrick's Day Parade and the New York City Marathon.

The Mounted Auxiliary Unit's annual budget is approximately $50,000. A large portion of the budget reflects the cost of renting horses and ongoing professional training. Thus far, most of the Unit's funding has come directly from the Auxiliary officers themselves and from a small, but growing, group of supporters. Because the Unit generates no earned income, and because Auxiliary officers cannot underwrite 100% of the costs associated with operating the Unit, new funding sources are continually being sought.