BACKGROUND:Identifying the characteristics of individuals who are most likely to respond to a certain rehabilitation intervention is advantageous for the child, family, clinicians and the healthcare system. AIM:To investigate the individual characteristics of children with cerebral palsy or brain injury who responded best to the Cognitive Orientation to daily Occupational Performance (CO-OP) Approach. METHODS:Post hoc analyses were conducted on 30 participants who participated in CO-OP within a larger randomized controlled trial. Inclusion: cerebral palsy or brain injury; age 4-15 years; Manual Abilities Classification System (MACS) I-IV; goals related to hand function; sufficient cognitive, language and behavioral ability to undertake CO-OP. Outcome measures were the Canadian Occupational Performance Measure (COPM) and Goal Attainment Scale (GAS) collected immediately following the two week intervention period. RESULTS:Following CO-OP, 67% (n = 20) of participants showed a statistically significant response on the COPM, and 73%(n = 22) on the GAS. Nine participants were classified as best responders. When compared to non-responders, best responders were more likely to be female (p = .025) and to have received a higher dose of CO-OP (p = .028). Neither age nor MACS were predictors of response. CONCLUSION:To be successful in CO-OP, children should meet the prerequisites of CO-OP, particularly the language and cognitive ability to set goals and communicate effectively with the therapist. In this small sample, children with comorbidities were less likely to achieve goals, females were more likely to respond and dose of therapy was important to success.