To determine the relevance of consumers' self-construal in social media contexts, this study investigates its effects on social media success metrics, such as sharing behaviour, as well as its influence on the relationship between social media success and other drivers, such as endorsers' emotion displays or the communication source (user vs. company). Along with an in-depth review of consumers' self-construal, this article reports on two quantitative panel studies, which reveal that eight items are best suited to represent consumers' self-construal, using correlated dimensions of interdependent and independent self-construal. The main study affirms the relevance of consumers' self-construal and offers detailed insights. Consumers with a strong interdependent self-construal express more positive attitudes toward social media posts, and a smiling endorser positively influences attitudes toward the post, sharing behaviour, word of mouth, and purchase intention. In combination, a strong interdependent self-construal and smiling endorser produce even stronger effects for attitudes toward the post, purchase intention, and word of mouth. User-generated content outperforms company-generated content, independent of self-construal types. These findings have important implications for social media communication management and personality research.