The quality of life of the elderly is one of the main concerns of sociologists today and comprises a major part of social life indicators. The sociological study of the effect of social capital on the quality of life of the elderly can lead to new planning endeavors and necessary reforms in optimizing the policies and plans in Iran. The purpose of this study was to compare the sociological impact of social capital on the quality of life of the traditional and modern elderly. This study was conducted as a survey using a randomly selected sample of the elderly in Rasht. Validity and reliability were verified using confirmatory factor analysis and Cronbach's alpha, respectively. The normality of variables was examined using Kolmogorov-Smirnov test. Moreover, the multivariate linear regression model was adopted, and using a stepwise regression, the ineffective variables were eliminated while the significantly effective ones were maintained. This way, a modified linear regression model was obtained for the quality of life of the elderly. A comparison of the two groups of traditional and modern seniors showed that from the perspective of modern seniors, family form transformation, social participation, urbanization, women's employment, cultural capital, generation gap, valuableness of the youth period, social changes, and technology have the highest positive effects on the elderly, respectively. However, from the viewpoint of the traditional elderly, spirituality, social capital, social participation, and government support have the strongest effects on the quality of life. The findings of this study can move the institutions and organizations toward paying more attention to social capital.