This chapter focuses on the bending folding behavior of composite tape springs, developing a theoretical model based on classical laminate theory and the minimum energy principle with the Newton-Raphson method to predict geometric configurations, folding moments, and longitudinal curvatures, considering tensile and bending strain energy contributions. Bending folding is classified into equal-sense (with bending-torsion coupling) and opposite-sense (highly nonlinear) modes, with the latter showing nonlinear moment-angle curves that peak, drop, and stabilize. The minimum energy principle deduces the propagation moment, dependent only on cross-sectional angle and bending stiffness. Experiments on metallic and composite tape springs validate the model, showing higher accuracy than Wuest, Yee, and Yao models. Strain energy analysis shows tensile energy dominance initially, shifting to bending energy when longitudinal curvature exceeds 0.0013 mm−1. Parametric studies find cross-sectional radius affects peak moment, while angle and thickness influence both peak and propagation moments.