There is confusion about the conceptual relationship between trust and social capital and classification and grading of the connections between these concepts is lacking. It is argued that the relationship between concepts of social capital and concepts of trust needs to be strengthened. The objective of this study is to explore the relation-ship between social capital and trust in various theoretical and empirical studies of social capital and to develop a classification system for grading existing concepts/conceptual fragments. A qualitative review of the research on social capital and trust within such disci-plines as sociology, political science and economics is conducted. The results show that there is a strong distinction between the subset and the input-output view. It is argued that locating the problem is necessary in order to avoid category mistakes and validity problems. It is suggested that the different categories should be treated separately instead of integrating them and that one should be explicit about it. The conclusions are that awareness of different categories allows one to pinpoint one’s position and movements on the “conceptual map”. Further one conceivable classification of existing ideas about the relationship between social capital and trust might be the one into subsets and input-output including a range of specific sub-ordinate categories. It is also concluded, that measurement issues are in focus for the subset view; explanation for the input-output view.