Case studies have pointed out that teachers' disciplinary knowledge affects their pedagogy; however, the results are not consistent. There is a need for quantitative research to examine the relationship between teacher knowledge and practice, particularly in social studies where content-specific studies are mostly qualitative. The authors used history as an example and surveyed all public and private junior high school social studies teachers in Taiwan to examine if disciplinary backgrounds significantly affect teachers' knowledge, conceptions about the discipline, and their teaching practices. Hierarchical linear modeling analyses show that disciplinary backgrounds significantly affect teachers' subject matter knowledge and pedagogy. Evaluations of effect sizes suggest that academic backgrounds can serve as useful proxies for teacher recruitment. The results also indicate that nature-revealing courses affect teachers' subject matter knowledge and pedagogy. (Contains 7 tables and 1 note.)