The present thesis considers the beam-columns that have a stochastic distribution of material and geometric properties, boundary conditions and loadings, and made of polymer-matrix fiber-reinforced composite material. Both the prismatic and thin-walled beam-columns are analyzed for their free-vibration response and buckling. In the case of thin-walled beam-columns, the local buckling occurs before the global buckling and therefore, the local buckling is considered in the stability analysis. Both the undamped free-vibration and static stability analyses are conducted based on a probabilistic approach. A detailed parametric study is conducted to determine the influences of various boundary conditions, the aspect ratios of flange and web sections of thin-walled beam-columns, the material, structural and geometric properties, their variabilities, laminate configurations, and the proximity of the applied axial loads to the critical loads, on the natural frequencies and buckling loads.