Based on consumer socialization theory, this study proposes and tests a conceptual model of social media shopping behavior, which links the antecedents of user motivations of engagement and peer communication about products to shopping behavior through social media. A cross-cultural survey was conducted with social media users in two culturally distinct markets with the largest Internet population: China (n=304) and the United States (n=328). Findings showed that social interaction, information, and remuneration were positive antecedents of peer communication for users from both countries. Peer communication positively impacted social media shopping behavior, and cultural differences were observed, with social interaction being important to Chinese users' shopping behavior, while remuneration was more important to American users. Implications are discussed.