During neuronal development, neuronal subtype differentiation is regulated by transcription factors (TF's) which control effector genes that define cell fate. TFs can regulate initial neuronal specification, the development of cell features (morphology, neurotransmitter expression, physiology) or both. The mammalian retina consists of 5 classes of retinal neurons with each type containing many subtypes. Detailing the specific roles TFs have in neuronal subtype specification and differentiation is important for understanding how neural circuitry develops and how morphological properties contribute to overall circuit function.