Experimental observation of the static and dynamic response of monocryst. lead magnesium niobate, Pb(Mg1/3Nb2/3)O3 (PMN), at moderate power continuous-wave laser irradn. showed five distinct regimes depending on the beam width and wavefront curvature of the incident Gaussian laser beam. In one of these regimes, the system exhibited multistability and transient aperiodic regenerative oscillations similar to those obsd. previously in ceramic PMN. In the other four regimes, thermal focussing and/or defocussing combined with nonlinear Fabry-Perot resonances to produce qual. different responses. The thermal relaxation time was calcd. theor. as 1-500 s, about 103 longer than earlier ests. and in agreement with expt. Damage thresholds are also discussed.