The aim of the paper is to present spatial variation of social capital in Poland, especially in relation to historical differences between various regions (resulting from the country’s partitions and border changes) and the level of urbanization. Previous studies indicate that such variation exists. However, they were carried out on the basis of declarations, an approach which has its drawbacks. This study uses a novel approach to assessing social capital: observing the behaviour of a study group using experimental economics, used in conjunction with a questionnaire which enables us to study the intention-behaviour gap. The study group consisting of 1540 individuals indicates very little variation between the regions. However, there are differences concerning the gap between declarations and behaviour in questions related to trust, trustworthiness, and cooperation, and our results confirm the conclusions from previous studies only weakly.