Many studies have noted the important role family socioeconomic status (SES) plays in students' out-of-school learning. However, very little is known about the relationship between students' SES and citizenship education in out-of-school contexts. To address this research gap, this study conducted an out-of-school citizenship education survey (involving 2,950 teachers, 7,388 students, 2,564 parents, and 112 out-of-school education organizations in Shanghai, China), in 2015, to explore the relationship between SES and students' out-of-school citizenship education. This article found SES affected primary and junior middle school (but not high school) students' participation in out-of-school citizenship education. This article adopted a power-knowledge relationship perspective to explain this pattern, and found that the relationship between education and power is not so mechanical that only powerful groups in society can determine knowledge and learning; instead, educational forces and students may mediate the influence of SES.