An experimental study has been made of the change in coercive force in thin ferromagnetic films when they are removed from a substrate. Only small changes in coercive force were observed for the iron and Permalloy films when the films were detached from the substrate. However, changes of up to 20 Oe were observed in the coercive force of nickel films. The magnitude of the change in the coercive force of nickel upon detaching the film from the substrate increased with film thickness and decreased for higher rates of thin-film deposition. The change of coercive force for nickel deposited on a substrate which has a thermal coefficient of expansion close to that of bulk nickel was essentially zero. The experimental evidence indicates that the observed changes in coercive force are due to differential thermal expansion between the substrate and the thin film.