The present invention relates to a bi-specific antibody or antibody fragment having at least one arm that is reactive against a targeted tissue and at least one other arm that is reactive against a targetable conjugate. The targetable conjugate encompasses a hapten to which antibodies have been prepared. In preferred embodiments, the hapten is histamine-succinyl-glycine (HSG). In more preferred embodiments, the at least one arm comprises the CDR sequences of the HSG-binding 679 antibody. The targetable conjugate is attached to one or more therapeutic and/or diagnostic agents. The invention provides constructs and methods for producing the bispecific antibodies or antibody fragments, as well as methods for using them and kits comprising them.