The Joint Numerical Testbed (JNT) program is a facility within RAL at NCAR that is connected to a broad network of collaborators. This includes cooperative research spanning academia, national labs, and government agencies, as well as international institutes and programs. The main goal of the JNT is to test and evaluate Earth System Models (ESMs, including Numerical Weather Prediction, NWP) and their components, with a focus on the hierarchical system development (HSD) approach and state-of-the-science verification methods, as well as developing and supporting community software in these areas. A large portion of JNT staff support projects for the NOAA-NCAR Developmental Testbed Center (DTC), which is focused on the transition of NWP model research into operations. Test results from JNT projects provide meaningful information about forecast performance for decision makers and for the broader ESM research community that supports development of these systems. The primary JNT activities cover regional and global modeling activities with an emphasis on process-level improvement.