Experiencing sibling conflict is a fact of life for most children, and this study investigates which form of sibling conflict is more likely to lead to adjustment difficulties such as anxiety and depression. Questionnaires enquiring about sibling relationships, anxiety and depression were administered to 121 students of Westland High School aged between 13 and 18 years. The correlations and multiple regressions performed indicated that adolescents with a positive sibling relationship have significantly lower levels of depression. In addition, emotional conflict between siblings was found to be a significant predictor of depression, whilst jealousy was found to be a significant predictor of anxiety and social phobia. Implications for intervention regarding disciplining emotional aggression and controlling for jealousy are discussed.