The electron spin resonance Linewidths of Mn2+ in single crystal MgO have been examined at both 9GHz and 30GHz over the temperature range 273K to 90K for manganese concentrations ranging from 880pprn to 4900ppm. For each of the doped crystals observations were made of the line width and line shape as function of polar angle; there were no changes in either 'g' value or hyperfine constant 'A' with polar angle over the temperature range. The predicted angular variations of line width for these manganese concentrations were also calculated, from the Van Vleck dipolar theory, and comparison showed that the observed linewidths were about sixty times less than expected. It was found that peak to peak linewidths were concentration dependent (closely following a (concentration) 1/2 law) and that Mn2+ entered the lattice substitutionally, occupying magnesium sites, even at the highest concentrations.