Oxytocin is a great facilitator of social life, but although its effects on socially-relevant brain regions have been extensively studied, oxytocin neuron activity during actual social interactions remains unexplored. The majority of oxytocin neurons are magnocellular neurons, which simultaneously project to the pituitary and forebrain regions involved in social behaviors. Here, we show that a much smaller population of oxytocin neurons, parvocellular neurons that do not project to the pituitary but which synapse onto magnocellular neurons, is preferentially activated by somatosensory stimuli. This activation is transmitted to the larger population of magnocellular neurons, which consequently show coordinated increases in their activity during social interactions between virgin female rats. Selectively activating these parvocellular neurons promotes social motivation, whereas inhibiting them reduces social interactions. Thus, parvocellular oxytocin neurons, receive somatosensory inputs to control social behavior by coordinating the responses of the much larger population of magnocellular oxytocin neurons.