Publisher Summary This chapter introduces the GABA, glycine and chloride cotransporters and their functions. The diversity of GABA and glycine's actions in mature nervous system are also discussed. It focuses mainly on the retina because the wealth of information regarding specific cell types and their functions in this tissue greatly facilitates the understanding of computations and performance of neuronal circuits. It also discusses the function of inhibitory neurotransmitters and cation-coupled Clˉ cotransporters in retinal development. The retina is a thin sheet of brain tissue that grows out into the eye to provide neural processing for image processing. The retina includes photoreceptors and two stages of neural processing. Its output cells project centrally and the information they convey is analyzed by about half of the cerebral cortex. Neuronal processes in the cerebral cortex can span millimeters to centimeters while in the retina the two synaptic layers span only 60μm, and most lateral processes span only several hundred μm. The general design of the retina encompasses several parallel feedforward pathways and many intricate feedback circuits. The feedforward pathways comprise three orders of hierarchical neurons that transmit information in two stages, using glutamate as their neurotransmitter.