The size-consistent self-consistent complete active space singles and doubles configuration interaction ((SC)(2)-CAS-SDCI) procedure has been applied to the calculation of vertical excitation energies, as well as the ionization energy, of the Rydberg radical ArH. Absorption oscillator strengths and Einstein emission coefficients for a number of electronic transitions have been obtained with the molecular adapted quantum defect orbital (MQDO) method. The adequacy of the two theoretical procedures employed in the present work is discussed.