We are excited to announce the beta release of OpenSim 4.5 and we would love to have your help in testing the new software! We would appreciate getting input by January 15. The new software includes improvements to the look and feel of the GUI, published Conda and Docker packages, additional Moco functionality, and the introduction of FunctionBasedPath for function-based muscle wrapping. We also now distribute a version of the Rajagopal model with the OpenSim resources folder included in the OpenSim application. A more detailed list of what’s new can be found here <https://simtk-confluence.stanford.edu:8443/pages/viewpage.action?pageId=130187315> We are looking for testers, whether you have time to test one thing or ten. To get started, install the OpenSim 4.5 Beta <https://simtk.org/frs/?group_id=91> (scroll down to "OpenSim Beta Releases") and visit the shared testing doc <https://docs.google.com/spreadsheets/d/1sN5xTI3ikd4xLOJH34eaom7c7lQuSmr6kk-iGpHmDjg/edit?usp=sharing> for instructions and a list of tasks to test. You can test out the bug fixes, try out the new features, or run through an example or two. Please don't hesitate to send any questions or feedback via email as well. Thanks in advance for your help! - The OpenSim Team