This paper presents the latest result on ongoing numerical simulation research of assembly and post-assembly analysis of MEMS devices. Evolving MEMS technologies, including the use of micro-fabricated hinges and gears, have enabled the fabrication of micro-assembled MEMS devices. Examples of these devices include tilting micromirrors, latching mechanisms, and micromotors. A simulation methodology has been developed that allows a MEMS designer to not only model the assembly process, but also to model the effects of various stimuli on the assembled device. Using these capabilities, a MEMS designer can investigate the necessary actuation forces, interfacing mechanisms, and time constraints for micro-assembly, as well as the performance of the device in its assembled state. These simulations rely on multi-stage non-rigid multi-entity contact analysis, dynamic analysis, and large displacement theory. Results are presented for a developed micromirror examples. The assembly process for the 'pop-up' micromirror mechanism are analyzed. After assembly, the coupled electromechanical actuation behavior will be studied. Changes in structural stress, stiffness, natural frequency, and mirror flatness are calculated and show a marked difference from the unstressed/undeformed shape. The newly developed algorithms allow designers to simulate and look into the details of phenomena often ignored in conventional MEMS design. Recent improvements in simulation methodologies allow micro- assembly analyses and post-assembly analyses of the resulting devices. By enabling micro-assembly and post- assembly analyses, we present the first reported MEMS analysis tool capable of modeling the latching mechanisms and post-latching actuation that frequently control current MEMS devices.