The multiphoton ionization photoelectron spectrum (MPI-PES) of C[sub 60] using pulsed lasers of nanosecond duration shows prompt electrons resulting from direct two-photon ionization, as well as a dominant low-energy delayed electron signal which follows an approximately thermal energy distribution with average energy [bar [epsilon]] = 0.30 [+-] 0.05 eV. The MPI-PES together with the mass spectrum at [lambda] = 193 nm suggests an important role of intersystem crossing from the singlet to triplet manifold of C[sub 60]. MPI at [lambda] = 193 nm is believed to result from such intersystem crossing followed by one-photon ionization of triplet C[sub 60]. Under this assumption, the photoionization cross section for C[sub 60] in the lowest triplet state is estimated to be (5.1 [+-] 2.0) [times] 10[sup [minus]17] cm[sup [minus]2]. 32 refs., 5 figs.