The present invention is based, in part, on the identification of novel antibodies that have binding affinity for both PD-L1 and PD-L2 and methods of using same. In one aspect, an isolated monoclonal antibody, or antigen-binding fragment thereof, which specifically binds both PD-L1 and PD-L2, is provided. In one embodiment, both PD-L1 and PD-L2 are human PD-L1 and human PD-L2.