Kuhn-McKearin, MeganTo date, the effects of the number of years students spend in special education on behavior outcomes has not been explored. This study sought to fill a gap in the existing literature by investigating the extent to which the number of years (i.e. duration) spent in special education and other aspects of special education (e.g. classroom setting and primary disability type) affected externalizing behavior in the fifth grade. Multiple regression analysis was used on data from the Early Childhood Longitudinal Study (ECLS-K; National Center for Education Statistics, 2002) longitudinal study to address the research questions. Results showed that longer placements were associated with higher rates of externalizing behavior. Additionally, receiving services in less inclusive settings and having a primary disability code of ED were associated with higher rates of externalizing behavior. Existing research findings and psychological theory were utilized to provide potential explanations for the results.enThesisSpecial educationPsychologyEducation policyemotional disabilityexternalizing behaviorinclusionspecial education