Developing efficient and accurate simulations of complex physical systems present numerous challenges. Numerical methods, software development, and computer science must come together with the driving science or engineering application in order to produce a truly usable simulation tool. In this presentation, I will discuss the mission of the US Department of Energy and overview a typical mathematician’s job at a DOE laboratory. I will include results from research and software code development in subsurface flow, climate, materials science, and power grid modeling demonstrating the benefits of multidisciplinary research and development teams. Carol Woodward is a computational scientist in the Center for Applied Scientific Computing (CASC) at Lawrence Livermore National Laboratory. She leads the Nonlinear Solvers and Differential Equations Project within CASC and is PI or co-PI on research projects in methods for climate simulation, dislocation dynamics, power grid modeling, and software development. Carol was named a Fellow of SIAM in the class of 2017. In 2015 she was one of 15 lab-wide recipients of the inaugural LLNL Early and Mid-Career Recognition Program Award. Carol has been a computational scientist with CASC since 1996. Prior to that time, Carol attended Rice University where she received her PhD in Computational Science, and Engineering. Previous to graduate school, Carol attended Louisiana State University where she received a B.S. in Mathematics.