Critical mass theory: An integrative conceptual review.

While the axiom that diversity is a competitive advantage has become commonplace, research has not provided a definitive answer regarding how much diversity is needed to attain this advantage. Critical mass theory proposes that a qualitative shift in group dynamics occurs when minority group representation reaches a threshold, strengthening members' influence on work processes and outcomes. We conducted an integrative conceptual review of 277 studies to evaluate and advance critical mass theory. Nearly a third of quantitative studies do not meet the methodological requirements for testing critical mass theory, including failing to model nonlinear relationships and lacking sufficient representation to detect a threshold. Among studies meeting methodological requirements, 83% support critical mass threshold effects, with a mean threshold of 29% (SD = 6.67%). Across methodologically sound studies, attaining a diversity critical mass is associated with improved interpersonal dynamics with downstream effects on employee satisfaction, the success of diversity and corporate social responsibility initiatives, misconduct, financial risk, innovation, organizational reputation, and performance. Critical mass effects are stronger and the threshold is lower when underrepresented members hold leadership roles, organizations operate in more equitable contexts, organizational and societal values align with those of the minority group, and organizations have stronger prior performance. Political divides and other within-group differences can hinder coordination among minority group members, weakening critical mass effects. Our review clarifies when and why a diversity critical mass contributes to competitive advantage and provides guidance for future research and for organizations seeking to leverage critical mass effects. (PsycInfo Database Record (c) 2026 APA, all rights reserved).