This paper by Q. He, Wang P and Ning Tian characterizes the developmental profiles of the light evoked excitatory and inhibitory synaptic inputs from ON and OFF synaptic pathways in the retina, the light evoked synaptic outputs and the sensitivity of the light evoked synaptic inputs and outputs to light deprivation of retinal ganglion cells (RGCs) and displaced amacrine cells (ACs) of developing mouse retina. The results strongly suggest that spontaneous and light-evoked synaptic activities of RGCs and ACs are regulated by different synaptic mechanisms.