Interdiction: Being happy is a response to how to live, especially for the young people who build the future of this land. Happiness produces passion, emotion, motivation, seeking and effort in the youth life and that’s the necessity of happiness. So, this study aims to examine relationships of social capital and its dimensions with happiness of young people.

Method: The method of research is survey. 380 individuals among the 15-29 year old residents in Babolsar city are the sample size. Data gathered through two kinds of questionnaires (modified Oxford happiness questionnaire and made of researcher social capital questionnaire).

Finding: Findings based on Pierson tests show that there is a direct correlation between independent variable of social capital and its dimensions with youth' happiness. Also, the most correlation of happiness is with social relation and the least is with formal participation.

Conclusion: The results of this research show that among the three dimensions of social capital, social relation and social trust along side with variable of economic-social status account for 25 percent of happiness.