"Casual car pools" are informal car pools that form when drivers and passengers meet at designated public locations. There are a number of East Bay pickup locations. Drivers drop passengers off at Fremont and Mission Streets (or nearby) in downtown San Francisco. Sometimes the driver will indicate where they are going after that (north of Market, for example, or even to Civic Center) and offer to take passengers further.

Casual car pools are quick and convenient. They are quick because in the morning car pools are able to bypass the long delays at the Bay Bridge toll plaza. In the evenings you can take advantage of the car pool-only on-ramp to the Bridge, and car pool lanes on I-80 and I-880. Car pools also do not pay tolls on either the Bay Bridge or the Carquinez Bridge during commute hours. Casual car pools are convenient because no pre-arrangement or fixed schedule is necessary. There are usually sufficient numbers of drivers and riders so that you can get a car pool within a matter of minutes.

The goal of Casual Carpool is to match commuters in order to reduce traffic congestion and to save money for both drivers and passengers by avoiding public transit fees and bridge tolls.

Casual car pool sites for rides to downtown San Francisco have been in existence in the East Bay for more than 20 years. Casual car pools are not "run" by any organization or authority. The "three-per-car" requirement helps to ensure safety, and passengers can always decline a ride if they feel uncomfortable.