The dominant mechanisms governing the anomalous diffusion of group III (B and Ga) and group V (P and Sb) elements in plastically deformed silicon have been investigated. The generation of vacancies by moving dislocations leads to the enhanced diffusion of B, Ga, and Sb in a lattice undergoing dynamic plastic deformation. A direct relationship appears to exist between the size of the solutes and the solutes' sensitivities to this enhanced diffusion mechanism. The presence of a great density of static dislocations does not measurably influence the diffusion of B, Ga or Sb. The diffusion of phosphorus into a crystal undergoing dynamic plastic deformation results in a `retarded' penetration of the diffused region relative to diffusion in a disorder-free lattice. This `retarded' diffusion effect is attributed to phosphorus precipitation.