ClN3 was photodissociated at 193 nm to produce NCl(a(1) Delta) in the presence of various chaperone gases. Room temperature rate constants for the collisional quenching of NCl(a(1) Delta) by these gases were determined from the time decay of the excited NCI. These rate constants were found to be 2.5 X 10(-12), 1.8 x 10(-11), 6.8 x 10(-13), 5.3 x 10(-13), 4.9 x 10(-12), 8.0 x 10(-12), 8.2 X 10(-13), less than or equal to 1 X 10(-15), and I 1 x 10(-15) for quenching by Oz, CL, Hz, D-2, HCl, DCl, HF, He, and Ar, respectively. The magnitudes of these rate constants are discussed in terms of crossings among the potential energy surfaces of bound amine-like intermediates. Photolysis of ClN3 at 249 nm produces NCl(a(1) Delta) which exhibits a time decay suggestive of chain decomposition of the azide parent. It is postulated that the chain is carried by vibrationally excited N-2.