This paper examines the impact of social capital on the quality of ideas generated by individuals at work. Two dimensions of social capital are compared – the degree (i.e. the size) of an individual’s network of work relations, and the structural holes (i.e. gaps between nodes) of those relations. Analyzing a database from a Swedish company which has worked systematically with idea management, and which today has a well-established information technology system that collects ideas from a large number of employees, this study presents evidence indicating that the larger is the size of an individual’s’ ego network – specifically the number of social interactions with other actors – the larger this individual’s innovative performance in terms of high quality ideas, whereas the larger is the number of structural holes in the ego network, the lower is the quality of ideas generated by the individual. Our findings support the conclusion that individuals’ relationships within firms play a key role for value-creating behavior, and thereby contribute to a deeper understanding of how social capital influences idea generation.