Complete-active-space self-consistent-field and multireference configuration interaction methods, and correlation-consistent polarized-valence quintuple-zeta basis sets, including up to g-functions, were used to describe the A(3)Pi-X(3)Sigma(-) transition of the SO radical. Potential energy curves, transition dipole moments over a wide range of internuclear distances, and radiative lifetimes for the A(3)Pi state are reported.