We make the case for an emergent notion of authenticity of science based on systems theory and neo-Piagetian thought. We propose that authentic science is an emergent property of a dynamic system of learning precipitated by the interactions among students, teachers, and scientists that occur within the contexts defined by the internal and external constraints of the cultures of the schools and communities within which they operate. Authenticity as an emergent property of the learning process challenges the basis for many science curricula and current pedagogical practices that take scientists' science as their norm and that assume a priori that such is authentic, i.e., it practices preauthentication. We argue that what constitutes authentic science can be taught neither in the traditional didactic modes nor through simulations of scientists' science in the classroom. Instead, authenticity needs to be seen as emergent and as diverse in meaning. To illustrate this point, we draw from two different face-to-face, teacher/student-scientist partnership programs. Both studies support a notion of authenticity that emerges as teachers, students, and scientists come to interact, make meaning of, and come to own the activities they engage in collaboratively. We conclude by considering the implications of such an analysis for science education. (Contains 1 table and 1 note.)