School mental health promotion evaluation can be viewed as a ‘new’ science that aims to establish the form and focus of evaluation that provides evidence of value for both education and mental health sectors for varying purposes.It builds on disciplinary knowledge from education, health promotion and mental health and well-being. It thus presents a number of challenges including: the need to clarify the purpose and focus of the evaluation and the methods and outcomes desired; the desired balance between evidence based practice and practice based evidence measures; the focus of the evaluation – resilience, social and emotional well-being; social support; school climate; mental health and mental illness as well as ethical considerations of teacher and pupil involvement. Techniques and approaches that have been proved valuable to address the complexity of evaluation include action based research; implementation of evidence based programs; program logic models and school audit tools.