Background: This study examined the ability of 78 children (aged 9-12 years) with an intellectual disability (ID) to provide a narrative account of a staged event they had participated in four days earlier. Method: The children were interviewed using open-ended questions. The quality of their responses (using a story grammar framework) was compared with that of two control groups: mainstream children matched for mental and chronological age. Results: While the children with an ID and those matched for mental age provided narratives of similar length and used similar proportions of each story grammar element, the ID group was less likely than both control groups to provide a narrative account at all. Among those children with an ID who did provide a narrative account, their accounts included proportionately fewer story grammar elements than those of both control groups. Conclusion: Children with an ID are disadvantaged as witnesses with respect to their ability to provide a detailed and coherent narrative account of events under optimal investigative interviewing conditions. (Contains 3 tables.)