Knowledge Management (KM) practice includes services designed to reduce the difficulty of sourcing knowledge, that is, getting the right knowledge to the right people at the right time. The phenomenon addressed in the study reported in this paper is a specific type of KM service -the Expert Recommending Service (ERS) -which contributes to achieving the difficult objective of getting the right expert to the right people at the right time. The findings of the study identify the dimensions of ERS success in different organizational contexts and the organizational characteristics that influence ERS success. Research contributions of the study are therefore two-fold. On the one hand, our results show that, among all the organizational characteristics, being aware of others, and specifically of others' knowledge domains, influences ERS success. On the other hand, our results suggest that ERS success can be significantly measured by employing the following dimensions: Quality, Use, Satisfaction, Individual Net Benefit, and Organizational Net Benefit. We also propose a set of recommendations for practitioners to help improve the success of their ERS, taking into account the informal expert recommending processes, improving the accessibility of all personnel to knowledge about their colleagues and considering the organizational characteristics, in particular awareness, before launching new ERS.