In December 1995, four new variable-toll express lanes were added to the median of a 16-km segment of California State Route 91 (SR-91). For those willing to pay the tolls, the new lanes provide an option to bypass congestion on the regular lanes. A special provision has initially allowed three-plus occupant vehicles to travel the congestion-free facility free of charge. A telephone survey of SR-91 travelers taken in fall 1996 provides insight as to how peak-period, peak-direction work commuters have responded to the new express lanes. Responses of 324 interviewed commuters are analyzed for changes in ridesharing, trends in express lane use, and differences in travel behavior among various socioeconomic groups. This research is important because public concern about fairness is a significant obstacle to the implementation of lane pricing. Two approaches are used to analyze changes in ridesharing and express lane usage. One approach focuses on usual travel behavior; the other focuses on the most recent work trip. The results of both approaches suggest that there has been an overall shift by commuters from lower to higher occupancy vehicles since the opening of the express lanes, and that express lane usage increases as the per person modal cost decreases. An aggregate analysis indicates that 23 percent of SR-91 commuters use the express lane for most of their work trips, and 46 percent never use the lanes. Statistical tests indicate that among two-occupant-vehicle commuters, household income influences express lane usage, and that among single-occupant-vehicle commuters, household type influences express lane usage.