Provided herein are novel anti-CD28 x anti-TROP2 antibodies and methods of using such antibodies for the treatment of TROP2-associated cancers. Subject anti-CD28 x anti-TROP2 antibodies are capable of agonistically binding to CD28 costimulatory molecules on T cells and TROP2 on tumor cells. Thus, such antibodies selectively enhance anti-tumor activity at tumor sites while minimizing peripheral toxicity. The subject antibodies provided herein are particularly useful in combination with other anti-cancer therapies, including, for example, bispecific antibodies for the treatment of TROP2-associated cancers.