Aim: The aim of this study was to examine the relationship between mastery motivation and individual and environmental characteristics in school-aged children with congenital hemiplegia. Method: Forty-eight child–caregiver dyads (children's mean age 7y 11mo, SD 2y 4mo; 33 males, 15 females; Manual Ability Classification System [MACS] level I, n=25, and level II, n=23; predominant motor type spastic hemiplegia, n=47) were recruited to this cross-sectional study. Children were assessed using the Melbourne Assessment of Unilateral Upper Limb Function (MUUL) and the Assisting Hand Assessment. Caregivers completed the Dimensions of Mastery Questionnaire, the Parenting Scale, and a demographic questionnaire. Results: Consistent and positive parental disciplinary practices were associated with higher total motivation (p=0.006) and instrumental aspect scores (p=0.009). Children with siblings and from single-parent families experienced greater negative reactions to failure (p=0.006). Children from two-parent families (p=0.018) and with better bimanual performance (p=0.015) demonstrated greater object-oriented persistence. Age, sex, limitations in manual ability (MACS), and movement and body function of the impaired limb (MUUL) did not contribute significantly to mastery motivation. Interpretation: Inconsistent, excessively lax, and verbose parenting practices may discourage children from persevering with challenging tasks. Functional parenting styles, positive discipline practices, and autonomy-supportive strategies for task engagement should be encouraged when intervening with children with cerebral palsy. Parents should be supported to engage in these practices in all aspects of daily activities.