This article presents a model for democratic pedagogy in science classrooms that is based on an examination of existing literature on democratic educational practices and on teacher and student ideas about how this pedagogy can take shape and be operationalized in science classrooms. A goal of democratic science pedagogy is to explore ways of teaching science for social justice among diverse school populations by drawing on the ideas and assets of students and teachers. Drawing upon interview and observational data, the model shows democratic science pedagogy as centered in constructions of community, shared authority, and critical science agency--students relying on subject-matter knowledge to make change and to redress power differentials in their lives. (Contains 2 tables, 2 figures, and 2 notes. This article was written with Angela Calabrese Barton.)