Our upbringing and education influence not only how we present and distinguish ourselves in the social world but also how we perceive others. We apply this central sociological idea to the social media context. We conduct a large-scale online study to investigate whether observers can correctly guess the education of others from their Facebook profile pictures. Using the binomial test and cross-classified mixed-effects models, we show that observers can assess the education of depicted persons better than chance, especially when they share the same educational background and have experience with the social media. We also find that posting pictures of outdoor activities is a strong signal of having higher education, while professional photographs can obscure education signals. The findings expand our knowledge of social interaction and self-expression online and offer new insights for understanding social influence on social media.