We aimed at using simple judgments of event segmentation to reveal cognitive problems in workers with intellectual disability regarding their assembly performance. We investigated event perception and assembly performance in 32 workers (mean IQ = 64.4). First, we assessed their ability to segment activity into meaningful events. The task involved segmenting four videos in coarse and fine events. We assessed event segmentation performance and compared it to 30 controls (IQ > 100). The workers detected fewer event boundaries than controls. A subgroup of the workers (12 of 32) defined more event boundaries in the coarse than the fine condition, indicating misconception of higher‐ and lower‐level content. The remaining 20 workers showed diminished hierarchical alignment compared to controls. Second, workers executed a Lego task. Better event segmentation performance was associated with enhanced assembly performance. These results suggest that the event segmentation task can serve as a diagnostic assessment for cognitive potential.Copyright © 2017 John Wiley & Sons, Ltd.