This article reports an ethnographic study of a molecular biology research laboratory, “Sally's Lab.” By studying the daily practices of the lab members, and interpreting these observations through an anthropological lens grounded in practice theory, I portray the social and cultural construction of a scientific community. Findings include an examination of how good science practice was operationalized, status in the lab was constructed, members gained or lost interest in continuing on in careers in research science, and individual members conformed to and resisted localized norms of scientific practice. These issues have direct relevance to our work as science educators, in terms of how we present science practice to our students. For example, when K–16 science students engage in activities based on authentic science practice, upon whose experiences are these simulations based? The current study shows that there is not just one acceptable way to do science, nor one set of experiences that pertain to all members within a given community of science practice. Likewise, there should not be just one way that science is presented in school, nor one set of experiences we expect all our students to take from our classes. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 387–407, 2001