The invention relates to novel TNF family ligand trimer-containing antigen binding molecules comprising (a) at least one moiety capable of specific binding to a target cell antigen and (b) a first and a second polypeptide that are linked to each other by a disulfide bond, characterized in that the first polypeptide comprises two ectodomains of a TNF ligand family member or fragments thereof that are connected to each other by a peptide linker and in that the second polypeptide comprises only one ectodomain of said TNF ligand family member or a fragment thereof.