Examined direct and mediated relations between condition parameters and maternal mental health for 53 mothers of 2- to 11-year-old children with juvenile rheumatoid arthritis (JRA). Multivariate analyses revealed that when considered simultaneously, indices of both biological severity and functional severity were associated significantly with maternal mental health. Further, mother's appraisals of the impact of the child's illness on the family partially mediated the effects of medication type and child's functional status on mother's mental health. Results provide support for conceptual models that emphasize the cognitive mechanisms by which condition parameters such as biological and functional severity might affect maternal mental health. Explicating the processes by which a child's JRA might lead to psychological adjustment problems in the parent has implications for developing preventive and treatment interventions.