Ohmic and Schottky barrier contacts with desired properties are difficult to form on GaAs devices. This is due mainly to the fact that the position of the Fermi energy is loosely ’’pinned’’ near midgap for GaAs surfaces which are metallized using conventional techniques. Doped alloyed metal ohmic and refractory metal Schottky contacts formed on carefully cleaned surfaces are currently widely used. New contacting techniques including the use of lattice matched heterojunctions, nonalloyed n++ and p++ surfaces, graded band gap structures, and special surface treatment prior to metallization promise to provide both greater flexibility and control for future applications.