This work presents our efforts to implement an MPI/OpenMP hybrid parallelization of the LIGGGHTS open-source software package for Discrete Element Methods (DEM). We outline the problems encountered and the solutions implemented to achieve scalable performance using both parallelization models. Three case studies, including two real-world applications with up to 1.5 million particles, were evaluated and demonstrate the practicality of this approach. In these examples, better load balancing and reduced MPI communication led to speed increases of up to 44% compared to MPI-only simulations. (C) 2015 Elsevier B.V. All rights reserved.