On March 9, 2012, the New York Academy of Sciences brought together experts representing a variety of perspectives—including academic, industrial, regulatory, as well as those from physicians and consumers—to discuss considerations for the non-biological complex drug (NBCD) regulatory approval pathway, given the emerging regulatory guidelines for biosimilars (follow-on biological complex drugs). Some of the organizers of the conference expressed their belief that NBCDs share a number of characteristic features with biologicals: the structure cannot be fully defined by the available (physicochemical) analytical tests, and quality assurance is based on in-depth knowledge, consistency, and control of the production process. However, their view on NBCDs was not universally accepted among the experts who participated in the conference. Plenary sessions addressed the most recent regulatory developments, experimental design, interchangeability, and immunogenicity issues for follow-on versions of complex drugs from the perspective of key audiences, including industry, regulatory agencies, physicians, and consumers. This report summarizes these various perspectives on NBCDs and the scientific and regulatory considerations associated with complex drug categories.