The question of theory change is crucial in knowledge construction, particularly in the process of conceptual change. This study was designed to investigate two factors that, in addition to initial theory preference, may play a crucial role in the process of theory change, that is, students’ interpretation of anomalous data on two controversial topics (the dinosaur extinction and the construction of the Giza pyramids in Egypt) and their epistemological beliefs about the nature of knowledge. Canonical correlation analyses suggested for both topics an association, stronger for the dinosaur extinction topic, between (a) acceptance of anomalous data (rated both as valid and inconsistent with the held theory), initial theory preference, epistemological belief in Certain Knowledge and (b) theory change. Data obtained from structure coefficients in canonical correlation analyses indicate that acceptance of anomalous data significantly contributed the most to theory change whereas the epistemological belief contributed the least. Finally, educational implications are drawn.