This study examined demographic- and personality-based employee dissimilarities in relation to organizational and interpersonal deviant behaviors. Perceived organizational support (POS), organizational commitment, perceived coworker support, and coworker satisfaction were proposed as mediators. The results revealed that dissimilarities in ethnicity, Agreeableness, and Openness to Experience were significantly related to organizational deviance; dissimilarities in gender, Conscientiousness, and Extraversion were significantly related to interpersonal deviance. In addition, ethnic dissimilarity negatively predicted POS and organizational commitment, age dissimilarity positively predicted perceived coworker support, Extraversion dissimilarity positively predicted coworker satisfaction, Agreeableness dissimilarity negatively predicted POS, and Openness to Experience dissimilarity negatively predicted POS, organizational commitment, perceived coworker support, and coworker satisfaction. Finally, POS partially mediated the relationship between Agreeableness dissimilarity and organizational deviance. Interpretations of results, implications for management, and future research are discussed.