Two different collapse models are developed for predicting the collapse resistance of encased pipes for pipe rehabilitation applications. One model corresponds to an unsymmetrical collapse mode and the other one corresponds to a symmetrical collapse mode. Attention is focused here on modeling the effect of the small radial gap between the encased pipe and the host pipe on encased pipe collapse resistance. This small radial gap is assumed to have developed when installing the encased pipe into the host pipe. It increases in size when subjected to temperature change, swelling, and application of external hydrostatic pressure. The predictions by the models correlate well with some collapse test results on encased pipes.