Nucleation of dislocations within a strained multilayer and at a singular or vicinal multilayer surface is considered for typical compound semiconductor and metal cases. The results indicate that strained multilayer structures are stable against dislocation injection, even when the layer thickness exceeds the thermodynamic critical thickness for misfit dislocation stability, in the absence of defects or large external stresses. An exact energy calculation for spreading of a threading dislocation in GaAs layer is also presented. The results show that in the absence of any jog formation, there is no barrier to spreading at or above the thermodynamic, Matthews–Blakeslee critical layer thickness. Moreover, reversible spreading to an equilibrium standoff distance occurs for thicknesses smaller than the critical thermodynamic value, an effect that can lead to dissipative reversed dislocation motion under alternating driving forces.