Active people with congenital absence or amputation of both lower limbs present fundamental prosthetic challenges that have not previously been addressed in the known literature. Those challenges are heat dissipation and the avoidance of thoracic skin shear trauma. The latter challenge is more significant in the subgroup of such people whose amputations are tertiary to spinal cord injury and pressure sores. The design reported in this paper consists of an air-permeable fabric socket suspended within a shell frame that promotes heat dissipation, reduces skin shear trauma, and permits upright weight-bearing and practical wheelchair function and mobility. The prosthesis is independent of the wheelchair and is self-suspending during transfers and nonwheelchair mobility. The prosthesis does not include legs and feet.