At least 1% of adults have autism spectrum disorder (ASD). However, very little research has been undertaken into how the lives of adults and older people with ASD can be improved. In this project, we will undertake the first stage of a programme of research into the lifecourse experiences of people with ASD. Experts in ageing and lifecourse, experienced ASD researchers, and people with ASD and relatives will undertake this project. We will engage with people with ASD, their parents, siblings and partners, and meet and discuss with them to understand much more about how ASD affects people’s daily lives as they age. During the first 3 years, we will work locally and nationally with clinicians, and the ASD community to identify at least 500 adults and older people with ASD, and around 500 relatives/carers who want to participate in a research cohort. We will ask adults with ASD, relatives and partners to complete questionnaires about their lifestories and health. We will also undertake one-to-one interviews and focus/discussion groups to identify common themes regarding aspects and periods of adults’ lives that have gone well, and those that they would like to have gone better. Adults and relatives will be invited to be recontacted by us to update information, and about future research studies that we, and other UK researchers, will undertake.Through understanding people’s lifestories, we will identify key priorities for future research. These topics and themes will then be pursued through future projects in partnership with the community, and other ASD lifecourse and ageing research groups.We will work in partnership with Autistica and the ASD community to effectively disseminate our research findings (including presentations, meetings, publications in scientific journals, research digests written by people with ASD, and open access and publicly available print and online media).