Organic semiconductors (OSC) are under widespread investigation for applications including organic thin-film transistors (OTFT), organic photovoltaics (OPV) and organic light-emitting diodes (OLED). The materials in these devices are selected or designed according to their intrinsic and extrinsic electronic properties with concern for efficient charge injection and transport, and desired stability and emissive properties. The chemical design space for OSC materials is enormous and there is need for the development of computational approaches to help identify the most promising solutions for experimental development. In this presentation we will present an overview of simulation approaches available to efficiently screen libraries of potential OSC materials; including first-principles prediction of key intrinsic properties, classical simulation of amorphous morphology, and quantum-mechanics evaluation of electron coupling for molecules in the condensed phase.