Over the past 10 years, antibody–drug conjugates (ADCs) have rapidly become an important player in the oncology therapeutic space. ADCs consist of three components: (i) A potently cytotoxic drug; (ii) An antibody that is designed to deliver the drug to specific antigen-expressing cells; and (iii) A linker that holds these two components together but is rapidly cleaved by cancer cells. Tremendous technical advances have been made in the ADC field over the past 15 years that have culminated in the FDA approval of six ADCs and the clinical evaluation (currently) of nearly 100 ADCs. This article provides an overview of the history of ADCs and highlighted important developments in the selection of antigens, design of the linker, selection of conjugation chemistry, and the design of the payload itself. We will focus on promising preclinical strategies that are working their way toward clinical evaluation.