In this progress report, the recent work in the field of light-emitting field-effect transistors (LEFETs) based on colloidal quantum dots (CQDs) as emitters is highlighted. These devices combine the possibility of electrical switching, as known from field-effect transistors, with the possibility of light emission in a single device. The properties of field-effect transistors and the prerequisites of LEFETs are reviewed, before motivating the use of colloidal quantum dots for light emission. Recent reports on these quantum dot light-emitting field-effect transistors (QDLEFETs) include both materials emitting in the near infrared and the visible spectral range-underlining the great potential and breadth of applications for QDLEFETs. The way in which LEFETs can further the understanding of the CQD material properties-their photophysics as well as the carrier transport through films-is discussed. In addition, an overview of technology areas offering the potential for large impact is provided.