Internationally, efforts are being made for educational practice to be research-informed on the grounds that schoolteachers will implement what research shows will "work". However, teachers do not necessarily accept research findings; sometimes they contest them. This article considers teachers' contestation in two empirical studies, using the concepts of denial, opposition, rejection and dissent as a framework for understanding such contestation. It finds three reasons why teachers contest research evidence: within-research issues, issues around generalising from research to practice, and non-congruence with personal values. These are explored with reference to the power differentials that are said to exist between research and practice.