Caltech is a small school, but oddly enough, the students sport quite a few cars. Part of the reason there are so many cars is that it is difficult to maneuver in Southern California without a car; people here aren't too big on public transportation. The professors, administrators, staff, graduate students, and undergrads all share the same parking. There are large parking structures and smaller lots all over campus. Parking on the street is allowed during the day, but Pasadena has strict laws about parking at night. Parking may be limited at times, but the school works to accommodate issues like this.
It is pretty easy for students to find parking. Students have small lots associated with each of the houses, which they can park in, as well as the large parking structures. Parking is often coordinated between partners who have keys to each other's cars, because some of the lots require blocking people in. There are very few assigned spots; most students just scavenge for parking when they return from their errands and park wherever there is an empty space. There are special slots for some professors and administrators, though. Students don't really need a car to get around campus or most of the necessary places, but a car can be a nice thing to have for weekend getaways to the beach or to LA. The biggest complaint that students have for parking is that it's half a block from most housing, and sometimes they have to use stairs because they have to park above ground level. Oh, cry me a river!