Through a case-study approach, the authors focus on understanding the complexity of teachers' knowledge development, particularly as it pertains to teachers' beliefs about literacy development and their teaching practices in literacy. Participants of the study are middle-school teachers who shared their beliefs and practices through (1) a semi-structured interview, (2) responses to an instrument designed to reveal teachers' beliefs about literacy, and (3) classroom observations. The case study of a teacher is presented to illustrate factors that can play a role as teachers strive to incorporate instruction compatible with their beliefs, thereby having implications for the professional development of teachers.