This study examined the relationships of the dispositional variables of hope, positive affectivity (PA), and negative affectivity (NA) with disease status and illness-related psychosocial functioning in a sample of 45 young adults with insulin-dependent diabetes mellitus (IDDM). Canonical analyses revealed one significant canonical function between the dispositional and psychosocial outcome variables. Primary contributors to the relationship were higher NA and lower PA and maladaptive emotional behavior. A linear multiple regression analysis using hope and affectivity as predictors failed to account for a significant proportion of variance in objective disease status as measured by hemoglobin A 1C (HbA1C). The results support previous findings that affectivity may relate to self-reported, disease-related outcome, but not necessarily to objective measures of health status. Future studies of adaptation to chronic illness should consider including measures of illness-related behaviors (e.g., adherence), as well as subjective and objective measures of health status.