We present nonrelativistic and quasirelativistic energy-adjusted pseudopotentials, the latter augmented by spin-orbit operators, as well as optimized (12s11p10d8f)/[8s7p6d4f]-Gaussian-type orbitals (GTO) valence basis sets for the actinide elements actinium through lawrencium. Atomic excitation and ionization energies obtained by the use of these pseudopotentials and basis sets in self-consistent field (SCF) calculations differ by less than 0.2 eV from corresponding, finite-difference all-electron results. Large-scale multiconfiguration self-consistent field (MCSCF), multireference configuration Interaction (MRCI), and multireference averaged coupled-pair functional (MRACPF) calculations for-thorium and thorium monoxide yield results in satisfactory agreement with available experimental data. Preliminary results from spinorbit configuration interaction,calculations for the low-lying electronic-states of thorium monoxide are also reported.