The Biologics Price Competition and Innovation Act of 2009 (BPCI Act) amends the PHS Act and other statutes to create an abbreviated licensure pathway for biological products shown to be biosimilar to an FDA-licensed biological reference product. This presentation will place into context the role of clinical studies in establishing a product as biosimilar to a reference product, including a discussion of PK and PD studies. We will use the two FDA approved biosimilar products as case studies. The FDA Advisory Committees’ reviews of these products provide examples to explore clinical study design issues particular to biosimilars, including margin determination and the relation of margins to clinically meaningful differences.