An equation for the activation energy of ionic conduction in silica glasses is developed. The approach uses the classical ideas of ionic crystal theory and elasticity theory. The equation finally derived involves the radius and valence of the modifier ion, the lattice constant of the glass, the electronic charge, the shear modulus, and three arbitrary parameters. Two of these parameters are shown to be related to the geometry of the silica network and are exactly determined from diffusion of gases in glass data. The other parameter is shown to be approximately numerically equal to the dielectric constant. he theory is compared with the experimental results of 140 glass compositions.