This paper describes a methodology for the analysis of classroom talk, called sociocultural discourse analysis, which focuses on the use of language as a social mode of thinking — a tool for teaching-and-learning, constructing knowledge, creating joint understanding and tackling problems collaboratively. It has been used in a series of school-based research projects in the UK and elsewhere and its use is illustrated with data from those projects. The methodology is expressly based on sociocultural theory and, in particular, on the Vygotskian conception of language as both a cultural and a psychological tool. Its application involves a combination of qualitative and quantitative methods and enables the study of both educational processes and learning outcomes. ABSTRACT FROM AUTHOR