While beneficial, the consistent and regular use of evidence to improve teaching and learning is proving difficult to achieve in practice. This paper attempts to shed new light on this issue by examining the question: "If using evidence to inform teaching practice is rational behaviour, why aren't all teachers engaged in it?" It first explores whether the evidence-informed practice (EIP) beliefs and perspectives of teachers align with their evidence-use behaviours; second it assesses what factors prevent teachers/schools that wish to engage in EIP from doing so. Using a Gradient Boosted Tree predictive model to analyse data from a survey of 696 practitioners in 79 schools, the findings suggest that, to increase EIP, school leaders need to: (1) promote the vision for evidence use; (2) illustrate how research enhances aspects of teaching and learning; and (3) establish effective learning environments. School leaders' broader commitment to EIP, and the interplay between EIP and accountability are also explored.