An ultimate goal of organic electronics is to fabricate large-area electronic devices and circuits on flexible and stretchable substrates. To achieve this target, understanding and/or tuning of the processes that determine charge transport is therefore of paramount importance for the development of high-performance devices, e.g., organic field-effect transistors (OFETs). Significant progress in this field is summarized here, with particular focus on the new insights of charge transport under certain strain effects in flexible and stretchable OFETs.