The present invention provides bispecific polypeptides, such as bispecific antibodies, comprising a first binding domain capable of specifically binding to a first T cell target, and a second binding domain capable of specifically binding to a second T cell target, wherein the first and second T cell targets are different targets. The invention further provides compositions of said bispecific polypeptides, as well as methods and uses of the same. The first and/or second T cell target may be selected from the group consisting of OX40, CTLA-4, CD137, CD27, GITR and CD28.