This case study explores the relationship between one chemistry teacher's conceptions of teaching science and his teaching practice. The teacher, Mr. Corrigan, comments on the researchers' interpretations of his thinking and practice. Mr. Corrigan exhibited a high level of disciplinary knowledge and clear views on teaching, learning, and content. His teaching focuses on laboratory work and his students' understanding of chemistry concepts, and he freely discussed his ideas of higher levels of thinking and "field trip" type experiences. Though these ideas were reflected in his practice, there were some tensions in the relationship between them and his directive teaching style and highly structured classroom and laboratory. Exploring these tensions with him revealed a pragmatic teacher thoughtfully dealing with the real world of his students and his discipline. (Author/PR)