Given transportation’s deep dependence on oil, the sector offers a litmus test for humanity’s collective ability to transition to low-carbon, socially just futures. This chapter discusses the potentials and challenges of low-carbon transitions in transportation. It reviews the multiple path dependencies that complicate such transitions but also argues that the prospects of positive change are now better than ever before. However, the realization of existing potentials requires that transitions in transportation are understood as full of social conflict and contestation and as demanding more than technological change and the deployment of economic policy instruments.