Non-Governmental Organizations (NGOs) have an important place in terms of fostering social capital, establishing social connections, and carrying out economic progress due to popular participation and involvement of institutions in the process. Social capital includes a collection of characteristics including interpersonal trust, reciprocity, mutual norms, social networks, and participation in civic engagement. The current paper deals with the concept of NGOs and social capital and highlights how they are related to each other in terms of supporting community development, social networking, cooperation, and common action. The paper also provides an insight into the definitions, types, and functions of NGOs, along with the history of social capital, its theoretical view, types, and method of measurement. The paper analyzes the types of social capital including bonding, bridging, and linking social capital in terms of providing interpersonal relations and connections between institutions and people. The contribution of NGOs to social capital development remains the core element of this paper due to the fact that this role is fulfilled by voluntary engagement and advocacy. NGOs contribute to social capital development through such activities as promotional efforts, mobilization of resources and community developmental activities. The importance of NGOs stems from the fact that they are the main agents of education, medicine, fight against poverty, nature preservation, women empowerment, and social governance. Moreover, NGOs work as mediators between communities and the government. In addition, the paper emphasizes the concept of social capital as an important tool and its contribution to creation of mutual trust among members of the society. The main idea of the paper is that NGOs are very important for developing social capital in terms of activating cooperation and collective responsibility.