| St. Charles Area Transit | |
| Headquarters: | 201 N. Second Street St. Charles, Missouri |
| Service Area: | St. Charles County, Missouri |
| Service Type: | Bus |
| Routes: | 5 |
| Fuel Type: | Diesel |
| Website: | SCAT Transit System |
St. Charles Area Transit, branding its service as SCAT, is a public transportation service located in St. Charles County, Missouri. The goal of the service is to provide mass transit access for these St. Louis, Missouri suburbs, which are not part of the city's Bi-State Development Agency transportation system. Four local bus routes are provided, plus one commuter route to St. Louis County, Missouri.
All of these routes converge on St. Charles O'Dell Senior Center.
Local environmental groups have been critical that SCAT isn't being serious enough to bring transit into St. Charles County, especially with urban sprawl in St. Charles County that is spilling over into Warren County, the construction of New Town in the floodplains of North St. Charles County, and several attempts by local civic leaders in O'Fallon and Dardenne Prairie to expand their civic plans across U.S. Route 40 into the Busch Wildlife Conservation Area.
Some have argued that St. Charles County resists expanding or integrating their transit system with St. Louis Metro Transit for fear of rising costs and a shift in ridership demographic. A few critics have accused St. Charles County's resistance due to "white flight" and the New Urbanism movement.