Understanding how scientific activities use naming stories to achieve disciplinary status is important not only for insight into the past, but for evaluating current claims that new disciplines are emerging. In order to gain a historical understanding of how new disciplines develop in relation to these baptismal narratives, we compare two recently formed disciplines, systems biology and genomics, with two earlier related life sciences, genetics and molecular biology. These four disciplines span the twentieth century, a period in which the processes (...) of disciplinary demarcation fundamentally changed from those characteristic of the nineteenth century. We outline how the establishment of each discipline relies upon an interplay of factors that include paradigmatic achievements, technological innovation, and social formations. Our focus, however, is the baptism stories that give the new discipline a founding narrative and articulate core problems, general approaches and constitutive methods. The highly plastic process of achieving disciplinary identity is further marked by the openness of disciplinary definition, tension between technological possibilities and the ways in which scientific issues are conceived and approached, synthesis of reductive and integrative strategies, and complex social interactions. The importance – albeit highly variable – of naming stories in these four cases indicates the scope for future studies that focus on failed disciplines or competing names. Further attention to disciplinary histories could, we suggest, give us richer insight into scientific development. (shrink)