Since classroom climate is inherently a group level phenomenon, we argue that measures shown to be valid and reliable in multi-level settings are needed. We propose a brief, 5-item measure of classroom climate and demonstrate its reliability and validity in multi-level structural equation models. The measure demonstrated good reliability and we also show the measure's relationship to a key student outcome, social emotional learning (SEL) knowledge. In classrooms with higher climate levels, fourth grade students are more likely to have higher SEL knowledge.