Background: Improved life expectancy means that more adults with intellectual disabilities are now living with ageing parents. This study explored older families' perceptions of the future. Methods: Semi-structured interviews were conducted with nine older parents and three adults with intellectual disabilities and analysed to produce an explanatory thematic framework. Results: "Tolerating uncertainty" was the major theme in participants' attempts to manage anxieties about the future, encompassing sub-themes of "accepting the parenting role", "facing challenges", "being supported/isolated", "positive meaning making", "re-evaluating as time moves on" and "managing future thinking". Some participants expressed preferences for their future which were in contrast to their parents' views, and provide a unique perspective that has often been neglected in prior research. Conclusions: This research has found commonalities in how families tolerate the uncertainty of the future, but also unique differences that require tailored interventions and prospective action by services.