We study the interactions among the interconnections between retinal neurons using electrophysiological and anatomical techniques. Neurons in cat, monkey, or pigeon retina are stained by the Golgi technique or by direct, intracellular injection of horseradish peroxidase (HRP) and subsequent histochemical reactions. The extents of dendritic and axonal arborizations of morphologically identified cells are illustrated in camera lucida drawings. Electrophysiological response properites are determined by intracellular recording. Electron microscopy reveals the synaptic relationships between photoreceptor, horizontal, bipolar, amacrine, and ganglion cell types. These data allow the inference of neural circuits and functional units within the retina and demonstrate the correlations between neural structure and function.