In the Ar II system transition probabilities are being calculated between states arising from the 3p44pand 3p44sconfigurations and between states of the 3p44sand 3p5configurations. We compare these calculations with previous theoretical and experimental work relating to the above‐mentioned transitions as well as to laser data. It is found that the various observed laser transition thresholds between the considered configurations are in reasonable agreement with the calculations. It appears that the various upper maser states are being pumped nonuniformly. It is also found that laser action should persist to rather high current densities. We estimate that, in 2‐mm‐diam tubes, output powers of at least 10 W/cm3of gas should be obtainable.