Background: Although mindfulness and yoga interventions for youth continue to gain support, few studies have proposed a systematic way to study the implementation and fidelity of these approaches. Objective: The current study developed and tested the feasibility of measurement procedures for a yoga and mindfulness curriculum implemented in schools through a community partnership. This was accomplished in two studies. Method: In study 1 we created and analyzed the psychometric properties of a fidelity observation tool using data from 165 observations of students receiving a district-wide school yoga and mindfulness intervention. The findings were subsequently refined and implemented to collect 91 additional observations in study 2. Results: In study 1, a principle components analysis revealed a 3-factor solution across items, with 10 of 17 items reliably rated but only 4 of those 10 items rated as satisfactory or better fidelity. The fidelity observation tool was then revised and implemented in study 2, with 13 of 17 items reliably rated and 5 meeting satisfactory or better fidelity. Conclusions: The findings from both studies indicated that yoga and mindfulness interventions for youth can be feasibly implemented and reliably measured within school settings, although there were some limitations in measuring both the content and process of such interventions.