The remarkable success of immune therapies emphasizes the need for immune-competent cancer models. Elegant genetically engineered mouse models of a variety of cancers have been established, but their effective use is limited by cost and difficulties in rapidly generating experimental data. Some mouse cancer cell lines are transplantable to immunocompetent host mice and have been utilized extensively to study cancer immunology. Here, we describe the Yale University Mouse Melanoma (YUMM) lines, a comprehensive system of mouse melanoma cell lines that are syngeneic to C57BL/6, have well-defined human-relevant driver mutations, and are genomically stable. This will be a useful tool for the study of tumor immunology and genotype-specific cancer biology.