This book outlines a novel methodology for simulating the nonlinear mechanical behavior of Structural Composite Lumber. The approach is based on stochastic finite element analysis and considers varying grain angle as well as mechanical properties of individual strands or veneers. The material of interest is angle-ply laminates although a preliminary investigation is also conducted on Parallam(R) Parallel Strand Lumber. Both 2 and 3 dimensional finite element codes are developed. The constitutive behavior of the wood strands is characterized within the framework of orthotropic elasto-plasticity. The constitutive model employs the Tsai-Wu yield criterion with the associated flow rule of plasticity. Weibull weakest-link theory is employed to adjust experimental tensile strength values for size effect. The programs are further formulated in a probabilistic manner using Monte Carlo simulations. Favorable comparisons of the model to experimental results attest to the effectiveness of the proposed technique.