Objective measures of schools’ wellness-promoting environments are commonly used in obesity prevention studies; however, the extent to which findings from these measures translate to policy and practice is unknown. This systematic review describes the comprehensiveness and usability (practicality, quality, and applicability) of existing objective measures to assess schools’ food and physical activity environments. A structured keyword search and standard protocol in electronic databases yielded 30 publications reporting on 23 measures that were deemed eligible to include in this review. Findings provide details to guide researchers and practitioners in selecting the best tool for use in policy and program evaluations.