Human resource capitals are considered as one of the most important resources for small enterprises. Considering the nature of these organizations, in the current trade world, social capital is an assuring criterion for organizational success. Due to the low number of employees in small enterprises, the leader has a more dynamic role in organizational processes and can lead the whole organization in to optimized usage of human resource. Moreover, by increasing effective communications, the leader can initiate and increase social capital. The role of transformational leadership style to generate social capital in small enterprises is discussed in this article. The population of this research is knowledge - base organizations in the 6th district of Tehran which are selected randomly. The measurement tool is a questionnaire distributed among 109 employees in 28 enterprises. Descriptive factor analysis is used To examine transformational leadership questionnaire's reliability, and 4 factors including inspiring communication, rational persuasion, supportive leadership- personal recognition and vision are identified. The results of this research which has been done on the individual level show that there is a positive and meaningful relationship between inspiring communication, rational persuasion, supportive leadership - personal recognition with social capital. Spearman relationship test also shows that there is a positive and meaningful relationship between transformational leadership and social capital. Then the discussion and conclusions based on these findings are discussed.