Background: The paradox of relying on routines and standard practices, which protect institutional functioning from the vagaries of personality, often comes at the cost of thoughtful adaptability. Purpose: The objectives are to conceptualize and apply the construct of mindfulness to schools and to explore trust as a school condition that fosters mindful actions. Setting: A diverse sample of 75 middle schools was selected for study. Participants: Twenty-six hundred teachers responded to survey instruments in 75 schools. Research Design: An ex post facto test of a theoretical set of hypotheses was performed. Data Collection and Analysis: Data were collected by researchers in regular faculty meetings and assessed using correlational, regression, and factor analyses. Findings: Faculty trust and school mindfulness seemed necessary conditions for each other. Conclusions: Mindfulness is a concept every school administrator should understand and practice, and a culture of trust seems necessary to achieve both the ends of understanding and practice. Principals need to lead in mindful ways. By encouraging faculty to play with ideas, to create novelty in their classrooms, to feel safe to take reasonable risks, to experiment, and to be resilient, the principal can have profound effects on school mindfulness. (Contains 5 tables.)