A new computer software program to score video observations, Video Observations Aarts and Aarts (VOAA) was developed to evaluate paediatric occupational therapy interventions. The VOAA is an observation tool that assesses the frequency, duration and quality of arm/hand use in children, in particular those with cerebral palsy. Reliability studies show that the first module, designed to evaluate a forced-use programme, has an excellent content validity index (0.93) and good intra- and inter-observer reliability (Cohen's kappas ranging from 0.62 to 0.85 for the three activities tested). With the built-in statistical package, paediatric occupational therapy departments can conduct therapeutic evaluations with children with impairments in the upper extremities. Further research is recommended to apply the VOAA in clinical studies in paediatric occupational therapy.