This chapter discusses the fundamental concepts behind distributed feedback (DFB) lasing, beginning with the underlying perturbation theory, which describes the lasing modes of a DFB laser. It describes the basic characterization/operation of an organic semiconductor DFB laser and offers a discussion of various fabrication techniques used to create organic DFB lasers. The chapter explores various design approaches to minimize the laser threshold, and provides the demonstration of indirect electrical pumping of an organic semiconductor laser using light-emitting diodes (LEDs). Fabrication of the DFB resonator requires the nanostructuring of an organic semiconductor waveguide on a sub-wavelength scale. The main techniques used to write the patterns are e-beam lithography and holography. Electron beam lithography is a precise, fine, and complicated technique used to create nanostructures. An alternative direct imprinting method that can mold the organic semiconductor layer is thermal imprint lithography (TIL). DFB lasers are highly affected by the particular design of grating used to create the cavity.