Researchers identified a methodology for obtaining the incremental societal costs and benefits for a variable pricing project and applied that methodology to the State Route 91 (SR-91) Express Lanes in California. This is the longest running variable pricing project in the United States and, as such, it provided useful historical data and trends upon which to estimate benefits and costs. This analysis found that the incremental societal benefits of the SR-91 Express Lanes exceeded costs for the time period considered. A companion paper that examines the benefits and costs of the QuickRide high occupancy/toll lane program found similar results. However, the magnitudes of the differences in benefits and costs were dramatically different for the two projects, indicative of their relative sizes and the numbers of travelers impacted. On SR-91, tens of thousands of travelers were impacted on a daily basis where QuickRide's impact was limited to approximately 400 travelers per day. Interestingly, the benefit-cost ratios of the two projects were similar, both between 1.5 and 1.7. 2006 ASCE.