This study investigates associations between initial levels and change in the quality of the relationships youth with intellectual disabilities (ID) share with their parents and teachers, and changes in their levels of depression over time. A sample of 395 youth with mild (48.3%) and moderate (51.7%) ID, aged between 11 and 22 (M = 15.69), were recruited in Canada (n = 142) and Australia (n = 253). Youth completed self-report measures of relationship quality and depression twice over a one-year period. Initial levels of warmth ([beta] = - 0.109) and conflict ([beta] = - 0.302) predicted decreases in depression. Increases in warmth predicted decreases in depression ([beta] = - 0.179), while increases in conflict predicted increases in depression ([beta] = 0.268). Discrepancies between youth relationships with their parents and teachers predicted decreases in depression ([beta][subscript warmth] = - 0.732; [beta][subscript conflict] = - 0.608).