We have developed and validated a general mathematical model for the dynamic behavior of the single-compartment respiratory system in response to an arbitrary waveform of applied inspiratory pressure. Our general model for ventilation applies to all integrable functions of applied pressure, and it enables computation of most ventilation and pressure variables of clinical interest from clinician-selected and impedance-determined inputs readily measured or estimated at the bedside. Interactions between both phases of the ventilatory cycle are considered by assuming that deflation occurs passively from a unicompartment lung. Because this flexible model appears both capable of accurate prediction and robust to major violations of its underlying linear assumptions, it may prove to be of value in a variety of scientific, educational, and clinical settings.