The quenching rate constants for NCl(a(1)Delta) by F and Cl atoms have been measured at room temperature to be (2.2 +/-0.7) x 10(-11) and (1.0 + 1.0/-0.5) x 10(-12) cm(3) s(-1), respectively, by adding F and Cl atoms to a flow reactor containing NCl(a(1)Delta). With knowledge of these quenching rate constants, the kinetics for the formation of NCl(a(1)Delta) from the Cl + N-3 reaction could be investigated in the F/Cl/HN3 reaction system. The reduction in NF(a(1)Delta) yield from adding Cl atoms to the reactor containing F and HN3 and the relative NF(a(1)Delta) and NCl(a(1)Delta) yields for known concentrations of F and Cl atoms in this reaction system favor a total Cl + N-3 rate constant of 3 +/- 1 x 10(-11) cm(3) s(-1) with a branching fraction for NCl(a(1)Delta) formation of greater than or equal to 0.5. The branching fraction was deduced from comparing the relative intensities of the NCl(a-X) and NF(a-X) transitions using a lower limit to the NCl(a) radiative lifetime of 2 s. The direct formation of NCl-(b(1)Sigma(+)) from Cl + N-3 is a minor channel; however, NCl(b(1)Sigma(+)) is formed by bimolecular energy pooling of NCl(a(1)Delta) molecules with a rate constant of approximate to 1.5 x 10(-13) cm(3) s(-1) and by energy transfer between NCl(a(1)Delta) and HF(upsilon greater than or equal to 2). The bimolecular energy-pooling process is a small fraction of the total bimolecular self-destruction rate for NCl(a(1)Delta).