Breathing is essential for survival and under precise neural control. The vagus nerve is a major conduit between lung and brain required for normal respiration. Here, we identify two populations of mouse vagus nerve afferent (P2ry1, Npy2r), each a few hundred neurons, that exert powerful and opposing effects on breathing. These neurons densely innervate the lung and send long-range projections to different brain stem targets. Npy2r neurons are largely slow-conducting C fibers, while P2ry1 neurons are largely fast-conducting A fibers that contact pulmonary endocrine cells (neuroepithelial bodies). Stimulation of P2ry1 neurons acutely silences respiration, trapping animals in exhalation, while stimulating Npy2r neurons causes rapid, shallow breathing. Activating P2ry1 neurons did not impact heart rate or gastric pressure, other autonomic functions under vagal control. Thus, the vagus nerve contains intermingled sensory neurons constituting genetically definable labeled l...