This study examines the sources of evidence that influence decision-makers who design or develop office buildings, and aims to explain why some managers engage more in evidence-based practice (EBP) than others. A mixed methods approach is conducted that combines quantitative results from 187 senior managers in the built environment and qualitative data from 18 interviewees. The respondents evaluated the use and trustworthiness of different sources of evidence, followed by an assessment of practitioners’ adoption and understanding of EBP. This study discovers notable differences between how practitioners and academics view EBP. The results highlight the importance of a manager’s learning goal orientation, the cultural norms of the work environment, and the industry-wide barriers for EBP. Implications for the adoption of EBP in the built environment at the individual, organisational, and industry levels are put forward.