The Standard Model of particle physics has been extraordinarily successful. Nevertheless, there are many observations which motivate particle physicists to look for and understand physics "beyond the standard model." My talk focuses on a major theoretical challenge in this task - the non-perturbative calculation of quantum chromodynamics (QCD) quantities. Starting with a description of the Standard Model, I will explain the role of QCD and the necessity of non-perturbative calculations. I will then describe our best tool for delivering precise, accurate, and even predictive calculations - lattice QCD. I will also review results which have given the particle physics community confidence in these complex calculations and point out directions of current research related to testing the Standard Model.