Organic field-effect transistors (FETs) are presently attracting significant academic research and industrial development interests as they offer performance capabilities comparable to those of thin-film amorphous silicon transistors but at the same time are compatible with low-temperature solution/printing-based manufacturing on flexible plastic substrates. In this paper, we review recent materials advances to improve the field-effect mobility of solution-processed organic semiconductors, discuss recent insight into the physics that determines the electronic structure at the semiconductor-gate dielectric interface in these devices, and provide an overview over some of the near- and medium-term applications.