The concept of misfit strain driving dislocations to an interface between two different phases leads to a residual strain that is not accommodated by the misfit dislocations. The residual strain occurs when the misfit stress is reduced to a value insufficient to generate further misfit-accommodating dislocations at the interface. This idea has been applied to epitaxial films to account for the relaxation of strain with increasing film thickness. It is here extended to the case of endotaxial interfaces between a solid matrix and precipitate. This paper builds upon work of Nabarro published in 1940 and the frictional stress to be overcome to move dislocations into the interface.