This article explores the impact of service quality, price, and word of mouth on the purchasing decisions of Restaurant D'cost Kemang in South Jakarta. The study collected data through questionnaires and found that service quality, price, and word of mouth all had a positive and significant effect on purchasing decisions. The article also discusses statistical tests and concepts related to regression analysis, such as homoscedasticity, heteroscedasticity, autocorrelation, the F-test, and the coefficient of determination. Overall, the study suggests that understanding consumer behavior and implementing effective strategies can improve business performance and market share in a competitive environment. [Extracted from the article]