<![CDATA[The increasing use of social commerce platforms, particularly TikTok Shop, has transformed how university students search for product information, interact with promotional content, and make purchasing decisions. This development highlights the growing importance of social media marketing in influencing consumer behavior among young consumers. This study aims to analyze the effect of social media marketing on purchase decisions among Universitas Sumatera Utara (USU) students who use TikTok Shop in Medan, Indonesia. A quantitative approach with an explanatory research design was employed. The population comprised active Universitas Sumatera Utara students who use TikTok Shop. Because the exact number of students who met the characteristics of TikTok Shop users and buyers was unknown, a non-probability sampling technique with purposive sampling was applied. A total of 100 active USU students who had made at least one purchase through TikTok Shop were selected as respondents. Data were collected using a five-point Likert-scale questionnaire and analyzed using simple linear regression with IBM SPSS. The results indicate that social media marketing has a positive and significant effect on purchase decisions, with a regression coefficient of 0.622, a t-value of 8.232, and a significance level of p < .001. The regression model was also statistically significant (F = 67.761, p < .001). The coefficient of determination (R² = .409) indicates that social media marketing explains 40.9% of the variation in purchase decisions, while the remaining 59.1% is associated with factors outside the model. Theoretically, these findings strendgthen empirical evidence regarding the role of social media marketing in shaping purchase decisions within the social commerce environment. Practically, businesses targeting university students should prioritize interactive, accessible, informative, and credible social media marketing activities to strendgthen consumer engagement and support purchase decisions on TikTok Shop.]]>
