In this chapter, we examine the conditions under which the single dislocation model is applicable. Using simple arguments, we demonstrate how the sign of the binodal slope determines the relative positions of the daughter- and mother-phase zones at the dislocation. We then adapt the general rescaling relations to the dislocation framework and derive the corresponding equations of state and motion in terms of dimensionless parameters. Finally, we present dimensionless expressions for the zone’s free energy and for the friction force acting on the propagating dislocation.