This thesis examines the role that parental casual attributions and the emotions associated with those attributions have on determining the level of stress a parent of a challenging child experiences. 60 parents of challenging children participated. Causal attributional dimensions and emotions were assessed in three scenarios in which a child displayed noncompliant behaviour. The children's levels of behaviours common to Attention Deficit Hyperactivity Disorder and Oppositional Defiant Disorder, and the level of parenting stress were also assessed. A mediation model was used for the analysis. The results supported full mediation, indicating that the relationship between child behaviour problems and parenting stress is mediated by the emotions that are associated with causal attributions following a child's noncompliance. Different mediational pathways were found for ADHD versus ODD behaviour.