Background: Children with intellectual disabilities (ID) have been found to have inferior motor proficiencies in fundamental movement skills (FMS). This study examined the effects of training the FMS of overhand throwing by manipulating the amount of practice errors. Methods: Participants included 39 children with ID aged 4-11 years who were allocated into either an error-reduced (ER) training programme or a more typical programme in which errors were frequent (error-strewn, ES). Throwing movement form, throwing accuracy, and throwing frequency during free play were evaluated. Results: The ER programme improved movement form, and increased throwing activity during free play to a greater extent than the ES programme. Furthermore, ER learners were found to be capable of engaging in a secondary cognitive task while manifesting robust throwing accuracy performance. Conclusions: The findings support the use of movement skills training programmes that constrain practice errors in children with ID, suggesting that such approach results in improved performance and heightened movement engagement in free play. (Contains 2 tables, 5 figures, and 1 footnote.)