<p>We develop nonlocal structural models for straight and curved MEMS/NEMS beam actuators, based on higher-order, Timoshenko, and Euler–Bernoulli kinematics. The governing equations are derived in two equivalent forms: a nonlinear differential-equation formulation and a Green’s-function integro-differential formulation. Numerical algorithms for both approaches are implemented in <b>Mathematica</b>, enabling consistent, side-by-side comparisons of accuracy and computational cost. The models are applied to study pull-in instability of nanobeams over a broad range of geometric (aspect ratio, thickness) and microstructural (nonlocal) parameters and for several boundary conditions. Results show that, for slender beams, all kinematic models provide similar predictions, whereas for relatively thick beams and/or strong nonlocal effects the higher-order and Timoshenko formulations are required for reliable estimates. Nonlocality produces a systematic softening of the response and can reduce the pull-in voltage by more than a factor of three relative to the classical (local) limit. The Green’s-function formulation offers improved numerical robustness and efficiency while remaining consistent with the differential-equation approach.</p>