OpenSim 2.0.1 is now freely available for download at: https://simtk.org/home/opensim. The OpenSim software enables modeling and simulation of human and animal movement, including inverse dynamics analysis and forward dynamic simulation. This new version includes static optimization to estimate muscle and joint forces. OpenSim 2.0.1 also allows modeling of contact and includes an application programmer’s interface (API) that enables software developers to call OpenSim functions from their own programs or Matlab. A User’s Guide and a Developer’s Guide are also available. The software, models, and example simulations are available at the project website. The project site also includes tutorials to help you get started and a forum for the user community. Our goal is to develop and disseminate technology for accurate simulation of musculoskeletal dynamics and to accelerate its appropriate use in movement science. Since its introduction in 2007, nearly 4000 biomechanists have used OpenSim to develop, test and share biomechanical simulations of movement. Please feel free to contact me or any one on the project team if you would like more information. Best wishes - Scott Delp (for the OpenSim Development Team)