Microstructural characteristics of a fully lamellar Ti49Al47Cr2Nb2 alloy have been investigated in annealed conditions by quantitative transmission electron microscopy studies. Statistical analyses have been performed to determine the distribution of orientation variants of the gamma phase and the nature of the gamma-gamma interfaces. Three sequences of lamellar transformation have been identified with decreasing temperature: (1) a high-temperature heterogeneous transformation, (2) a homogeneous transformation in the ordered alpha(2) phase, and (3) a coherent transformation at alpha(2)/gamma interfaces. The driving forces for these various transformations are discussed.