Heat-transfer rates in laminar film condensation on the underside of horizontal and inclined surfaces are predicted by assuming the condensate flow to be the quasi-steady result of a bounded instability. This assumption makes it possible to determine the final shape of the liquid-vapor interface, and thus predict the average heat-transfer coefficient. Measurements of the heat-transfer coefficient obtained by condensing Freon-113 were found to agree quite well with the values predicted by this method. Several distinct regimes of flow in the condensate film were observed. On the underside of horizontal surfaces, the interface is best described as a fully established Taylor instability. At slight angles of inclination there are three regimes of flow. Near the leading edge, the interface is smooth and waveless. Next there is a region of developing waves which are best described as elongated drops or longitudinal ridges. As the ridges grow in amplitude, drops form at the crests and subsequently fall from the surface. beyond the point at which drops first fall, a third regime exists which can be considered to be a fully developed state, independent of distance from the leading edge of the surface. At moderate angles of inclination and up to the vertical, “roll waves” appear a short distance from the leading edge.