Selected Constants Relative to Semi-Conductors presents the physical constants of semiconductors in Table form. The values of the electronic properties of semiconductors presented in the Table are parameters intended for use in theoretical and phenomenological equations relative to the band theory for these materials. In addition to data specific to band structure, the Table also includes mobilities of electrons and holes and their variation with temperature. Data of a general physical character are also presented, since the researcher very often finds use for values of this type. The following quantities are given when available: symmetry group and crystal parameters, refractive index, dielectric constant, effective ionic charge, work function, photoemission work function, piezoresistance coefficient, elastic coefficients, phonon temperature, Debye temperature, magnetic susceptibility, coefficient of linear expansion, fusion temperature, sublimation temperature, specific heat at constant pressure, latent heat of fusion, latent heat of sublimation, thermal conductivity, disorder factor, and density.