Newly observed instances of reverse migration, i.e., migration from urban to rural areas, suggest the possibility that the labor market adjustment process could be unstable. We provide a theoretical analysis of this conjecture using a Harris-Todaro-Lewis model. A bifurcation analysis is presented that shows how various stable and unstable adjustments are possible including chaotic fluctuations and how these possibilities are related to adjustment speed, the productivity of industry and agriculture, and the relative importance of industry and population size. Examples of unstable adjustments in a hypothetical LDC and DC are given using "plausible" parameter values.