$Introduction:$ Breathlessness is a common symptom of advanced disease placing a huge burden on patients, health systems and informal carers (families and friends providing daily help and support). It causes distress and isolation. Carers provide complex personal, practical and emotional support yet often feel ill-prepared to care. They lack knowledge and confidence in their caring role. The need to educate carers and families about breathlessness is established, yet we lack robustly developed carer-targeted educational interventions to meet their needs.

$Methods:$ We conducted a qualitative interview study with twenty five purposively-sampled patient-carer dyads living with breathlessness in advanced disease (half living with advanced cancer and half with advanced chronic obstructive pulmonary disease (COPD). We sought to identify carers' educational needs (including what they wanted to learn about) and explore differences by diagnostic group in order to inform an educational intervention for carers of patients with breathlessness in advanced disease.

$Results:$ There was a strong desire among carers for an educational intervention on breathlessness. Six key topics emerged as salient for them: 1) understanding breathlessness, 2) managing anxiety, panic and breathlessness, 3) managing infections, 4) keeping active, 5) living positively and 6) knowing what to expect in the future. A cross-cutting theme was relationship management: there were tensions within dyads resulting from mismatched expectations related to most topics. Carers felt that knowledge-gains would not only help them to support the patient better, but also help them to manage their own frustrations, anxieties, and quality of life. Different drivers for education need were identified by diagnostic group, possibly related to differences in caring role duration and resulting impacts.

$Conclusion:$ Meeting the educational needs of carers requires robustly developed and evaluated interventions. This study provides the evidence-base for the content of an educational intervention for carers of patients with breathlessness in advanced disease.