Retinal amacrine cells are thought to lack chromatic or color-selective light responses and have only a minor role in color processing. We found that a type of mammalian (Ictidomys tridecemlineatus) amacrine cell selectively carries a blue-On signal, which is received from a blue or short wavelength-sensitive (S) cone On bipolar cell. This glycinergic inhibitory S-cone amacrine cell is ideally placed for driving blue-Off responses in downstream ganglion cells.