Recent work on the characterization of the second‐order, mean‐field, valence transition in Ce1−xThx is briefly reviewed. Extended work has culminated in the quantification of the Landau free energy functional which describes the transition. The understanding of the microscopic origin of the different terms in the free energy is illuminated by measurements of the specific heat and the effects of solutes of varying valence and atomic size. Results for thermopower and magnetic susceptibility are also presented and are utilized to characterize the integral and non‐integral valence states. Throughout, comparisons are made with the SmS system.