An antibody-T cell receptor (TCR) chimeric molecule (abTCR) that specifically binds to a target antigen, comprising: a) a first polypeptide chain comprising a first antigen-binding domain comprising V H and C H 1 antibody domains and a first T cell receptor domain (TCRD) comprising a first transmembrane domain of a first TCR subunit, wherein the first polypeptide chain lacks variable and constant domains of the first TCR subunit; and b) a second polypeptide chain comprising a second antigen-binding domain comprising V L and C L antibody domains and a second TCRD comprising a second transmembrane domain of a second TCR subunit, wherein the second polypeptide chain lacks variable and constant domains of the second TCR subunit, wherein the V H and C H 1 domains of the first antigen-binding domain and the V L and C L domains of the second antigen-binding domain form an antigen-binding module that specifically binds to the target antigen, wherein the target antigen is a cell surface antigen or a complex comprising a peptide and a major histocompatibility complex (MHC) protein, wherein (i) the first TCR subunit is a TCR α chain, and the second TCR subunit is a TCR β chain; (ii) the first TCR subunit is a TCR β chain, and the second TCR subunit is a TCR α chain; (iii) the first TCR subunit is a TCR γ chain, and the second TCR subunit is a TCR δ chain; or (iv) the first TCR subunit is a TCR δ chain, and the second TCR subunit is a TCR γ chain, and wherein the first TCRD and the second TCRD form a T cell receptor module (TCRM) that is capable of recruiting at least one TCR-associated signaling module; wherein optionally the antigen-binding module comprises a disulfide bond between a residue in the C H 1 domain and a residue in the C L domain. a) a first polypeptide chain comprising a first antigen-binding domain comprising V H and C H 1 antibody domains and a first T cell receptor domain (TCRD) comprising a first transmembrane domain of a first TCR subunit, wherein the first polypeptide chain lacks variable and constant domains of the first TCR subunit; and b) a second polypeptide chain comprising a second antigen-binding domain comprising V L and C L antibody domains and a second TCRD comprising a second transmembrane domain of a second TCR subunit, wherein the second polypeptide chain lacks variable and constant domains of the second TCR subunit, wherein the V H and C H 1 domains of the first antigen-binding domain and the V L and C L domains of the second antigen-binding domain form an antigen-binding module that specifically binds to the target antigen, wherein the target antigen is a cell surface antigen or a complex comprising a peptide and a major histocompatibility complex (MHC) protein, wherein (i) the first TCR subunit is a TCR α chain, and the second TCR subunit is a TCR β chain; (ii) the first TCR subunit is a TCR β chain, and the second TCR subunit is a TCR α chain; (iii) the first TCR subunit is a TCR γ chain, and the second TCR subunit is a TCR δ chain; or (iv) the first TCR subunit is a TCR δ chain, and the second TCR subunit is a TCR γ chain, (i) the first TCR subunit is a TCR α chain, and the second TCR subunit is a TCR β chain; (ii) the first TCR subunit is a TCR β chain, and the second TCR subunit is a TCR α chain; (iii) the first TCR subunit is a TCR γ chain, and the second TCR subunit is a TCR δ chain; or (iv) the first TCR subunit is a TCR δ chain, and the second TCR subunit is a TCR γ chain, and wherein the first TCRD and the second TCRD form a T cell receptor module (TCRM) that is capable of recruiting at least one TCR-associated signaling module; wherein optionally the antigen-binding module comprises a disulfide bond between a residue in the C H 1 domain and a residue in the C L domain. <EOS>