Although social groups have “insiders,” this construct has not been measured within the disability advocacy community. Examining 405 individuals who applied for an advocacy training program, this study examined the nature of insiderness within the disability advocacy community and ties to individual roles. Participants showed differences in mean ratings across 10 insider items. A principal components analysis revealed two distinct factors: Organizational Involvement and Social Connectedness. Non-school providers scored highest on Organizational Involvement; family members/self-advocates highest on Social Connectedness. Themes from open-ended responses supported the factors and showed differences in motivation and information sources across insiderness levels and roles. Qualitative analysis revealed two additional aspects of insiderness not addressed in the scale. Implications are discussed for future practice and research.