Private vehicles are a significant source of air pollution in many areas of the United
States. Areas with already high levels of air pollution are required by the Clean Air Act
to take steps to reduce automobile use and the associated emissions. The behavioral
implications of many travel demand management techniques are poorly understood. In
this dissertation I focus on carpooling. Policy makers encourage commuters to carpool
through High Occupancy Vehicle (HOV) Lanes, free parking for carpoolers, attempts to
connect carpoolers, and casual carpoolers (often called slugging). Despite these