Perfectionism is a putative risk factor for depressive symptoms. However, most research in this area uses cross-sectional designs (which fail to address temporal precedence) and mono-source designs (which are influenced by various biases). The present study overcomes these limitations by using a novel design involving both self- and informant reports of self-critical perfectionism (i.e., negative reactions to perceived failures, concern over others’ criticism and expectations, doubts about performance abilities, and intense self-rebuke). It was hypothesized that self- and informant reports of self-critical perfectionism would correlate moderately and that self- and informant reports of self-critical perfectionism would predict increases in depressive symptoms over time. A sample of 155 target participants and 588 informants was recruited and studied using a prospective longitudinal design. All study hypotheses were supported, including evidence that self- and informant reports of self-critical perfectionism each add incrementally to the understanding of the self-critical perfectionism–depressive symptoms connection. Informant reports may provide a complete picture of the self-critical perfectionist and her or his vulnerability to depressive symptoms.