A dynamic model of a microcantilever actuator is developed to simulate the events of contact, impact, stiction, and pull-off from the substrate. The model accounts for geometric, electrostatic, adhesive, and contact nonlinearities. The model is validated by comparison to experimental data and other analytical model predictions. We find that microcantilever electrostatic microelectromechanical (MEMS) actuators can exhibit bistable and tristable equilibrium configurations. We also find that the transients subsequent to pull-in play an important role in determining whether or not stiction will occur.