The relationships between selected condition characteristics and self-esteem were investigated in a randomly drawn, community-based sample of 286 young adults with chronic illnesses and disabilities. Whether appraisals of the impact of the condition mediated relationships between condition characteristics and self-esteem, as measured by the Rosenberg Self-Esteem Scale, was also measured. As a group, the youth in this sample reported positive self-esteem. When sociodemographic and condition-related variables were considered simultaneously, maternal education, unpredictability of symptoms, prognosis, sensory impairment, and the presence of a co-occurring learning disability were found to have direct effects on esteem. Perceived impact mediated the relationship between condition characteristics and self-esteem. The results are discussed in relation to the role of impact appraisal in determining the emotional well-being of young adults with chronic illnesses.