The effect of both temperature and composition on the rate of transformation of a nematic phase from an isotropic solution is examined from a theoretical standpoint. The kinetics of the transformation are presented as a time–concentration–temperature–transformation (TCTT) diagram, analogous to the time–temperature–transformation (TTT) diagrams commonly used in metallurgical process design. The transformation is regarded as a nucleated process in which the transformation rate is proportional to the number of stable nuclei, and this in turn depends on a balance between the energy gained by nematic ordering and the energy expended in forming the nematic–isotropic interface. The nematic ordering term is estimated as a function of both concentration and temperature via two different approaches: (i) the lattice theory as described by Flory and Warner and (ii) the Maier–Saupe theory of nematic ordering. Although there are differences in detail, both approaches yield the same qualitative result. The present work provides the details necessary for developing a specific example application of our recently reported generalized system-independent model of nucleation and growth. The TCTT diagram is in essence a phase diagram augmented by kinetic information for nematic ordering, and thus is expected to be a powerful graphical tool in liquid crystal process engineering and other applications.