[en] The bulk damage performance of potassium dihydrogen phosphate crystals under simultaneous exposure to 1064, 532, and 355 nm nanosecond-laser pulses is investigated in order to probe the mechanisms governing damage initiation during frequency conversion. The results provide insight into the dependence on laser parameters of the defect-assisted excitation process responsible for coupling of the laser energy into the lattice under exposure to high power laser light. In addition, it is suggested that the damage performance can be directly related to and predicted from the damage behavior of the crystal at each wavelength separately