This study focuses on how the accessibility and quality of co-workers in organizations affect their use as information source. Prior research has produced inconsistent findings concerning these factors’ respective influence on source selection. In this article, we argue that one potential reason for this lies in the lack of coherent definitions of accessibility and quality. To bridge this gap, we unpack these concepts into their underlying dimensions, based on insights derived from social capital theory, more specifically Nahapiet and Ghoshal’s contribution, to uncovering the multidimensionality of social capital. We empirically test the dimensionality of accessibility and quality, as well as the relative influence of these concepts on human information source selection, in a scenario experiment within an organization. Findings support the proposed dimensionality, and lead to the conclusion that both quality and accessibility influence the selection of human information sources, although quality exerts a slightly stronger influence.