This article analyzes the emergent new discipline known as chemical biology as part of the rapidly developing postgenomic research agenda. Despite chemical biology's academic as well as political significance in terms of its expected contribution to drug discovery, the international STS community has failed to pay serious attention to its dynamism thus far. The objective of this paper is to fill this gap by conducting a case study on the rapid formation of the Japanese Association of Chemical Biology, which is a global pioneer, in 2006. By bridging different theoretical concerns, namely laboratory studies in STS and the study of policy process, particularly the theory of policy window by Kingdon, this paper analyzes how three different levels—laboratory practices, community of scientists, and policy process—are mutually constitutive, and why both Japanese scientists and policy makers believe that chemical biology is important both in science and policy. This paper will substantiate the all-encompassing notion of coproductionism given by Jasanoff, by emphasizing more specific instances such as the role of policy entrepreneurs, international competition, and sense of scientific tradition, which are crucial for enabling coproduction.