The transport refrigeration systems used in trucks and trailers are an integral component of the cold chain for perishable foods, pharmaceuticals and other temperature-sensitive products. The technology used in these systems is continually evolving to meet food quality standards, as well as current and future regulatory requirements for greenhouse gas emissions. Additional technologies have enabled greater fleet management and control, as well as reductions in customer operating costs. The present talk provides a summary of transport refrigeration requirements, along with an overview of available technologies used to address them and a discussion of the related technical challenges and design tradeoffs.