In this study, we sought to create and validate a brief measure to assess students' perceptions of kindness in school. Participants included 1,753 students in Grades 4 to 8 attending public schools in a large school district in southern British Columbia. The School Kindness Scale (SKS) demonstrated a unidimensional factor structure and adequate internal consistency. The pattern of associations of the SKS to a corpus of theoretically relevant constructs obtained via student self-reports (classroom supportiveness, optimism, happiness, prosocial and social goals, satisfaction with life, and academic self-efficacy) provided evidence for convergent and discriminant validity. Furthermore, the SKS was significantly and positively associated with teacher reports on students' empathy, social skills, and peer acceptance. Analyses by gender and grade indicated that girls perceived significantly higher levels of kindness in school than did boys, and that students' perceptions of kindness in school decreased from fourth to eighth grade, with fourth-grade students reporting the highest levels of kindness in school and eighth-grade students reporting the lowest levels. The theoretical importance of investigating students' perceptions of kindness in the school context and the practical implications of this research for informing educational efforts to promote social and emotional competencies in school communities are discussed.