Using a prospective design we examined the nomological network of positive and negative perfectionism by considering relations with optimism, pessimism, neuroticism, conscientiousness, and variables of health and psychological well-being. Positive perfectionism was found to have a large amount of variance in common with optimism and conscientiousness and negative perfectionism was found to share a large amount of variance with pessimism and neuroticism, but not enough to be considered redundant in either case. Importantly, both positive and negative perfectionism were found to add significant incremental validity to the prediction of the criterion measures even after controlling for the influence of time one variables. Implications of these findings for future research on perfectionism are discussed.