Self-accommodation morphology of the α ″ martensites in Ti–Nb shape memory alloys with Nb content ranging from 20 to 24 at.% was investigated. Hollow and solid triangular morphologies consisting of three α ″ variants were found to be the α ″ self-accommodation morphologies. The α ″ variants are related to each other by twinning on { 1 1 ¯ 1 } α ″ . A V-shaped morphology consisting of two α ″ variants coupled with a solid triangular morphology consisting of three α ″ variants was found to be another type of self-accommodation morphology. The α ″ variants from the V-shaped morphology are related by twinning on { 1 1 1 } α ″ , whereas the α ″ variants from the solid triangular morphology are related to each other by twinning on { 1 1 ¯ 1 } α ″ . Pairs of crystallographically equivalent { 1 1 ¯ 1 } α ″ twinning dislocations with steps of opposite signs were found to cause the overall orientation of the twinning terraces and steps to be parallel to the { 1 1 ¯ 1 } α ″ twinning interface.