Micro-air-vehicle wing designs often incorporate flexible structures that mimic the skeletal and membrane attributes found in natural flyers. Accurate performance predictions for these wing types require coupling of aerodynamic and structural simulations. Such fluid–structure interaction simulations are often performed using high-fidelity, numerically expensive techniques such as computational fluid dynamics coupled to nonlinear structural finite element analysis. Although the computational cost of conducting many conceptual design trade studies with these methods is prohibitive, simplified approaches may lack sufficient fidelity to provide conceptual design insights. This paper summarizes the development, comparison, and application of an efficient fluid–structure interaction method to simulate flexible-wing performance for rapid conceptual design of micro air vehicles. An advanced potential flow model computes aerodynamic performance, whereas a corotational frame and shell finite element structural model computes wing deflections due to aerodynamic loading. The paper reviews existing computation approaches, then describes the model formulation, aerodynamic load coupling algorithm, comparisons with a higher fidelity method, and aeroelastic results of wing flexibility parametric and optimization studies at chord-Reynolds numbers of about 75,000. For one specific 304.8 mm wingspan planform, carrying a 0.45 kg payload, the studies indicate the optimized flexible wing achieves 7% endurance parameter gain compared with the stiffer baseline wing.