The entire 30 Omega states generated from the 12 valence and two Rydberg Lambda-S states of the BS radical have been studied at the MR-CISD + Q level of theory for the first time. The effects of spin-orbit coupling and the avoided crossing rule between electronic states of the same symmetry were analyzed. Spectroscopic constants of several excited states that have never been observed in experiment were obtained. The transition properties of several low-lying bound excited states to ground state transitions, including the transition dipole moments and the Franck-Condon factors, were also calculated, from which the corresponding single-channel radiative lifetimes were derived. (c) 2005 Elsevier B.V. All rights reserved.