On the basis of activities of a federally funded national center for school mental health, review of literature on principles for best practice in child and adolescent mental health and school health, and consultation with national experts and family members, a set of 10 principles for best practice in school mental health was developed. A survey was developed enabling 1-6 point Likert ratings ("clearly unimportant" to "clearly important") for each of the 10 principles. With an original sample of 426 people involved in education, school health or mental health, all 10 principles were strongly endorsed, receiving mean ratings ranging between 5.10 and 5.75. On the basis of qualitative feedback from this survey and interactive forums, language for 9 of the 10 principles was revised and a survey reflecting these changes was developed and administered to a validation sample of 86 respondents. As with the original sample, endorsements of the principles were strong, with mean ratings ranging between 5.45 and 5.79. Findings are discussed in relation to advancing interconnected agendas related to quality assessment and improvement and empirically supported practice in school mental health.