This application describes binding proteins that specifically bind to EGFRvIII and multispecific binding proteins that specifically bind to EGFRvIII and CD3. Further described is a multispecific tandem diabody that binds to EGFRvIII and CD3. Further described are highly cytotoxic EGFRvIII/CD3 bispecific tandem diabody for recruiting T cells to specifically and potently kill several types of solid tumor cance