This article aims at presenting different approaches to the phenomenon of social capital. The concept of social capital is ambiguous and that is why we will highlight a number of definitions of this notion. The central attention of the paper focuses on the relationship between social capital and regional development and competitiveness. The fundamental question concerns the impact of social capital on the regional economic performance. Hence, we will survey the empirical examination of 16 Polish regions in terms of social capital. We will also study whether the regional level of social capital depends on the level of competitiveness. The purpose of this article is also to make a contribution to the discussion concerning the relationship between economic development and social capital.