In situ phase transformation experiments have been carried out using neutron and synchrotron X-ray diffraction to monitor the texture evolution and establish the criteria for variant selection during the α → β → α phase transformation in Zr-2.5Nb. There is clear evidence of a strong variant selection occurring during the α → β transformation and a weaker variant selection during the β → α transformation. Further, comparing hot-worked specimens with those that have received additional cold-work revealed that cold-work introduced microstructural characteristics that inhibited the full development of the transformed texture seen in the hot-worked samples. A study of the effect of external biasing stresses during transformation was conducted. An external biasing stress was applied along the hoop axis during different components of the α → β → α transformation. An external stress during heating does not appear to significantly influence variant selection, at least for the stress magnitudes tested here, while an external stress during cooling did have some influence on the resultant texture.