Provided herein is an antibody- or antibody fragment-targeted cationic immunoliposome complex prepared by a method comprising the steps of (a) preparing an antibody or antibody fragment; (b) mixing the antibody or antibody fragment with a cationic liposome and to form a cationic immunoliposome wherein the antibody or antibody fragment is complexed with the cationic liposome, but is not chemically conjugated to the cationic liposome and wherein said antibody or antibody fragment does not comprise a lipid tag; and (c) mixing the cationic immunoliposome with a therapeutic or diagnostic agent to form the antibody- or antibody fragment-targeted cationic immunoliposome. Also provided is an antibody- or antibody fragment-targeted cationic immunoliposome comprising an antibody or antibody fragment; a cationic liposome, wherein the antibody or antibody fragment is complexed with the cationic liposome, but is not chemically conjugated to the cationic liposome and wherein said antibody or antibody fragment does not comprise a lipid tag and a therapeutic or diagnostic agent.