This article systematically reviews the literature noting unplanned meetings of the principal or unplanned principal meetings (UPMs) from 1970 to 2022. UPMs are understudied though they are considered essential for communication and/or labeled as distractions. The purpose of this review is to examine notations of UPMs in academic literature to estimate how much principal time they comprise and what purposes they serve. The systematic literature search used keyword search, snowballing, and personal network references to yield 31 academic publications. The interpretive findings of the review suggest that UPMs comprise at least 16% of principal workdays and provide information exchange, crisis management, and emotional support. UPMs fulfilled these purposes through their informality, candidness, immediacy, and confidentiality. UPMs epitomize that small does not mean simple. Even though they usually take under 5 min, they shift the school principal time, attention, and space and carry the potential to shift school and school leadership practice. Significantly, the everyday, little-noted UPMs manifest the work tension and work intensity of principalship and may serve as a novel lens to theorize principal practice.