The aims of this study were to develop an instrument to measure parents' responses and perceptions related to the onset of either seizures or asthma in a child (aged 4-14) and to assess the initial reliability and validity of the instrument. The 35-item scale developed comprised five subscales: Child Support, Family Life/Leisure, Condition Management, Child Autonomy, and Child Discipline. Subjects were parents of 224 children with new-onset seizures and 104 parents of children with new-onset asthma. Internal consistency reliabilities were stronger for Child Support, Family Life/Leisure, and Condition Management than for Child Autonomy and Child Discipline for both samples. Test-retest reliability ranged from good to fair for both samples. The associations between parent positive mood and all of the subscales for both samples in the predicted directions provided key empirical support for validity. The scale has potential for use in research and in the clinical setting. In addition, the scale has potential to be used with other conditions.