摘要:This report theorizes and provides empirical evidence of how researchers and educators might recognize categories of teachers’ knowledge for teaching as teachers teach and discuss with peers their student’s mathematical behavior and their practice. Its theoretical orientation engages work by Shulman on pedagogical content knowledge, Ball and Bass on mathematical knowledge for teaching, and Steinbring on teachers’ epistemological knowledge. The empirical evidence emerges from the practice of teachers working with working class African American and Latino students in a poor, urban school district in the United States of America. The results of this investigation, part of larger, broader inquiry, suggest that the categories of teachers’ knowledge implicate each other. Key words : teaching and learning, teacher training, teaching practice, teaching of mathematics