A molecular film of pulmonary surfactant covers the hydrated lung epithelium to the air. We recently showed that the film exhibits a locally strongly variable electrical surface potential of up to several hundred millivolts. The potential arises from aligned molecular dipoles of the molecules. In the case of the complex structural organization of the phase-separated film of pulmonary surfactant, a map of the local surface potentials allows insight into the local distribution and order of its molecular constituents. Here, we summarize our recent findings and discuss how the electrical surface potential influences the architecture of the film but also changes the way how the lung interacts with the environment.