This article presents one portrayal of the role of photography as a language of teacher inquiry. To inform teachers' use of photography, the first part of the article presents a brief historical perspective of photography's role in the study of human behavior in the fields of visual anthropology, visual sociology, photojournalism, and media literacy. The second part of the article includes three functional applications of photography in teacher inquiry: representational, mediational, and epistemological. The three functions are defined, and classroom examples and in-depth analyses of these functions are provided to illustrate how photography promotes inquiry-based classroom practices. These analyses include discussions of teachers' intentional focus or mental lens, the importance of collective contexts of teacher study, the metacognitive processes of teacher inquiry, and the appropriation of skills in teacher inquiry. Each example demonstrates a progressively deeper analysis of how photography can be used by educators to move the field of education toward visual literacy. The examples are taken from preschool and early elementary-school classrooms, although the applications may be extended to the broader field of education.