Extended Abstract
Introduction: Social solidarity in different times, crisis conditions or periods of prosperity and growth, increases the ability of citizens to cooperate and discipline, and thus plays a role in shaping positive practices. In the path of national development, social solidarity can increase the content of people’s participation in social institutions, pave the way for social reform in society, and reduce the likelihood of internal strife. Therefore, considering the impact of social solidarity in the development of societies and the fact that solidarity is the basis of any kind of planning and policy in society, recognizing it can be a great help for development. Meanwhile, Shahrekord, with a combination of different ethnicities of Lor, Turk, Fars, etc., undoubtedly needs development and progress, and to achieve this, it needs a certain amount of social solidarity. Therefore, in order to move towards development and progress, it is necessary to obtain information about the level of social solidarity and the factors affecting it in this city with the help of a scientific research, and then to provide solutions to strengthen social solidarity for sustainable development of this city. With regard to this issue, the present study has tried to take responsibility for this important issue.
Method: The theoretical framework of this study is a combination of sociological theories (Tonies, Park and Chalabi) that in a hypothetical model of the relationship of three independent variables (government satisfaction, socialization and social trust) with the variable of social solidarity. The statistical population of this study was all citizens aged 17 and over (both men and women) living in Shahrekord, who according to the latest population and housing census (2016), 159775 people. Using Cochran’s formula and taking into account the variance, the sample size is 385 people who have been selected based on multi-stage cluster sampling method. Data collection tool is a researcher-made 56-item questionnaire and its reliability is 0.768 based on Cronbach’s alpha table, which shows that the research tool is reliable. Data analysis of this study was performed using Amos software.
Findings: The results indicate that the level of social solidarity for 38 people (9.9%) of the subjects at a low level, for 176 people (45.7%) at a medium level and for 171 people (44.4%)  Is at a high level; In other words, the level of social solidarity among the citizens of Shahrekord is moderate to high. There is also a significant relationship between the variables of government satisfaction, socialization and social trust with social solidarity. Meanwhile, the variable of socialization (β = 0.62) had the greatest impact on the variable of social solidarity. 
Discussion: The concept of social solidarity has long been considered by social scientists, but the shift of concepts from the field of hard concepts to soft concepts in the developed world has made the consider of this concept much more serious in recent decades; So much so that with the increasing complexity of society and the increasing degree of individualism, social solidarity has been considered necessary for the continuation of collective life and the facilitation of actions, and especially social order. In other words, social solidarity in today’s society plays a pivotal role in social participation, productivity, political legitimacy, social order, bonding and solidarity, and development in general. According to the findings of the research, the following strategies are proposed to strengthen social solidarity:
Considering that the higher the level of satisfaction with the government, the higher the level of social solidarity, so the government is obliged to provide the ground for the flourishing of economic, political, cultural and social spheres with its strategic policies, so that in its shadow. 
Considering that socialization has the most significant effect on social solidarity, it is possible to increase the level of solidarity by expanding this process. socialization can refer to family, school, religion, or :union: activities. Socialization is not limited to the above, but also includes a variety of social interactions, such as foreign and domestic travel, the use of media, including written, spoken, audio, and family gatherings.
Since social trust has impact on social solidarity, so in this case can be increased by expanding trust in various dimensions (individual, social, political, etc.) the amount of solidarity in society.

Ethical consideration
This article is extracted from a research project entitled “Sociological study of social harmony in Shahrekord” with the financial support of Payame Noor University of Chaharmahal and Bakhtiari province and methodological guidelines of Dr. Yahya Ali Babaei. The authors were fully involved in the preparation of this article. This article does not overlap with other published works by the present authors; Also, in this article, all the rights related to research ethics have been observed.