The issues that challenge prosthetic liner and sleeve manufacturers are age-old: durability, residual-limb volume fluctuations, temperature and moisture control, and skin health. The solutions that are in development, however, are entering a whole new world. Innovations range from elegantly simple advances to amazingly sophisticated breakthroughs involving embedded computerized sensor systems. As elevated vacuum prosthetic technology grows in popularity, liners and sleeves will undoubtedly play a significant role. New, “smart” materials that can repair themselves or change their shape, thickness, softness, or durometer in response to changes in the socket environment to maintain fit and comfort may also step forward.