Social sustainability today, as the most important dimension of sustainable development, has an important place in urban planning and its importance in planning is constantly increasing with the increase of social problems and divergence between neighborhoods in terms of performance and participation. Therefore, this requires more research in urban studies. This study was conducted to investigate the role of social participation in the development of social sustainability in neighborhoods. For this purpose, the significance of the significant effect of these two variables has been measured. The research is applied in terms of purpose and descriptive-analytical in terms of method. Data collection was library and field method. The statistical population of the study consists of a group of experts who were selected by the available method of 20 people as the sample size of the study. Data collection tool is a questionnaire based on theoretical foundations and studies conducted on a five-point Likert scale. Data analysis was performed using structural equations with the help of Emus software. The results showed that the social participation of citizens in neighborhoods with a coefficient (beta) of 0.732 has a positive effect on sustainable social development of these neighborhoods and the relationship between these two variables is significant. In other words, sustainable social development will be strengthened by strengthening social participation. And the variables of sense of belonging, satisfaction with the neighborhood, participation in neighborhood activities and trust also have a positive effect on the variables of social participation in neighborhoods.

In the creation of urban space, there is always an exchange of ideas about what the space is now and how it should exist, by those who live in that place. So improvement in its harsh reality is realized in some of their thoughts in the form of a physical change in the current environment - and urban regeneration is one such form. Considering the increase in the number of urban regeneration projects in recent decades, it is very important to pay attention to the social dimensions in it. On this basis, social capital, as one of the social potentials of the neighborhood, is a concept that has gained special importance in regeneration. Considering the necessity of the subject, this research has analyzed the role of social capital on the regeneration of urban neighborhoods. The applied research method is descriptive-analytical in nature and the main goal of this research is to analyze the role of social capital in the regeneration of Islamabad Karaj neighborhood among the residents of the neighborhood. In this regard, the data collection in the theoretical part was based on the documentary method and in the practical part, the survey was based on the questionnaire. The statistical population of this research is made up of people over 15 years of age living in a neighborhood of over 25,000 people using a simple random sampling method, so a sample of 410 people was selected from this population using Cochran's formula. For data analysis, Spearman's correlation coefficient and multiple linear regression were used using spss software. The results showed a strong correlation between social capital and urban regeneration in Karaj neighborhood of Islamabad. The implications of this research on the relationship between social capital and urban regeneration increase the need to pay attention to the components of social capital and adopt policies to maintain and promote it in order to ensure successful urban regeneration in the neighborhood of Islamabad Karaj.