Survey data from more than 1,000 large employment sites in the San Francisco Bay Area are used to examine the link between transit use and proximity to rail stations. The data were collected as part of an employer trip-reduction rule. Findings show that sites within one-quarter mile of a rail station have significantly higher rates of transit use than sites between one-quarter and one-half mile from stations. Transit use drops even further one-half mile from stations. That relationship holds true for all three rail systems in the Bay area. A closer look at 20 work sites near two light rail stations in Santa Clara County reveals that actual walking distance is also an important factor related to transit use. However, site design often lengthens walking distance unnecessarily. In addition, certain types of employers have higher rates of transit use than others.