Social media have become ubiquitous in our lives. To meet with the calls to examine social media usage in cross-cultural contexts, the study conducted a longitudinal survey to explore bilateral relationships between social media usage, self-efficacy and cultural intelligence. Based on Social Cognitive Theory, findings indicate that both informational and socializing usage of social media increase individual’s self-efficacy whereby individual cultural intelligence is developed. In addition, cultural intelligence effectively enhances increasing of individual’s self-efficacy. Implications and limitations are further discussed.