Background The purpose of this study was to investigate the relationship between depression, hopelessness, problem-solving ability and self-harming behaviours amongst people with mild intellectual disabilities (IDs). Methods Thirty-six people with mild IDs (77.9% women, M[subscript age] = 31.77, SD = 10.73, M[subscript IQ] = 62.65, SD = 5.74) who had a history of self-harm were recruited. Participants were asked to complete measures of depression, hopelessness and problem-solving ability. Results Cutting was most frequently observed, and depression was prevalent amongst the sample. There was a significant positive relationship between depression and hopelessness, while there was no significant relationship between self-harm and depression or hopelessness. Problem-solving ability explained 15% of the variance in self-harm scores. Conclusions Problem-solving ability appears to be associated with self-harming behaviours in people with mild IDs.