This study investigates how congruence between social and knowledge ties affect group information sharing, specifically, the bias against sharing unique information (Stasser & Titus, 1985). Three-person groups composed of two familiar individuals and a stranger participated in a complex decision making task in which some information was held by all group members, while some critical information was uniquely held by individuals (adopted from Stasser & Stewart, 1992). In the “congruent” condition, the two familiar members in each group possessd the same information while the stranger held unique information. In the “incongruent” condition, one of the familiar members held unique information while the second familiar member possessed the same information as the stranger. We hypothesized that whereas congruence between social and knowledge ties would enhance information sharing effectiveness by reinforcing cognitive schema and allowing members to focus on the task, incongruence would interfere with information sharing by upsetting the social order. Discussion content analyses supported this prediction. Congruent groups shared more unique information and solved the problem more effectively than incongruent groups. Implications for managing diversity in organizational work groups are discussed.