<p>Subjective well-being (SWB) has been extensively studied globally, with much of the research focusing on the average effects of its determinants. However, few studies have explored the heterogeneous impacts of these factors on SWB across regions and country levels. Our study addresses this gap by examining how key determinants—including demographic, material, and non-material factors—affect individuals at different quantiles of the SWB distribution across 149 countries. Using Gallup World Poll data and quantile regression, our study investigates how the impact of these determinants varies across different segments of the population and compares these effects with the average effects. The results show that, on average, being male and having a large household size are negatively associated with SWB, while having children, higher education, employment, income, and civic engagement are positively linked. Specifically, financial stability, optimism, positive experiences, diversity, and basic community services positively influence SWB across all quantiles. In contrast, education, future optimism, social relations, and physical health have stronger positive effects at the lower end of the SWB distribution. Based on these findings, this research suggests that policymakers can enhance SWB through targeted investments in mental health programs and emotional support networks that can benefit low-SWB groups. Expanding educational and employment opportunities for disadvantaged populations may enhance future optimism and self-efficacy. Strengthening community infrastructure and social spaces can foster attachment and cohesion, especially in urban and low-income settings.</p>