What does it mean to take a socio-cultural perspective on science education? Most basically it means viewing science, science education, and research on science education as human social activities conducted within institutional and cultural frameworks. What is the scope of a socio-cultural perspective on science education? Let us take the key terms of the previous broad description as our starting points. What does it mean to view the objects of our concern as “social activities”? In a research perspective it means, first of all, formulating questions about the role of social interaction in teaching and learning science and in studying the world, whether in classrooms or research laboratories. It also means giving substantial theoretical weight to the role of social interaction: seeing it, as in the Vygotskyan tradition (Vygotsky, 1963; Leontiev, 1978; Cole, 1996), to be central and necessary to learning and not merely ancillary. Similarly, it means seeing the scienti®c study of the world as itself inseparable from the social organization of scientists’ activities, as is done in the work of Bruno Latour and many other contemporary sociologists and historians of science (e.g., Latour, 1987; Lynch & Woolgar, 1990, Shapin & Schaffer, 1985). But this is only the beginning. Interpersonal social interaction, whether collaboration in a laboratory or dialogue in a classroom, is only the smallest scale of the social. Socio-cultural theory proposes that such cooperative human activity is only possible because we all grow up and live within larger-scale social organizations, or institutions: family, school, church, community center, research lab, university, corporation, and (depending on your particular theory) perhaps also city, state, global economy, and even a potentially globe-spanning Internet chat room or listserv group. Our lives within these institutions and their associated communities give us tools for making sense of and to those around us: languages, pictorial conventions, belief systems, value systems, and specialized discourses and practices. Collectively such tools for living our social semiotic resource systems and our socially meaningful ways of using them constitute the culture of a community. Taking an ecological view of communities, we should also include as parts of such ß 2001 John Wiley & Sons, Inc. an ecosocial system all the artifacts and natural species and materials people employ in making use of these tools. Finally, socio-cultural theory emphasizes that all human activity functions on multiple scales, from the physiological to the interactional to the organizational to the ecological, and so also on the corresponding time scales from the momentary to the biographical, historical, and evolutionary.