In 1979 Schoemaker became involved in the founding of Centocor together with a former Corning Medical colleague Ted Allen and the bioentrepreneur Michael Wall with whom he had some dealings while at Corning. Inspired by the work of Hilary Koprowski, who developed some of the earliest monoclonal antibodies against tumour antigens and influenza viral antigens, the objective of Centocor was to commercialise monoclonal antibodies for diagnostics and therapeutics. In 1980 Schoemaker joined Centocor and soon after became its first chief executive officer.