Community-based, do-it-yourself (DIY) archives and museums of popular music are cultural institutions that can serve important social and affective functions. In this article, we examine how DIY heritage institutions create a sense of community and promote wellbeing for their volunteers, operating as informal gathering spaces, or “third places.” Using the Australian Jazz Museum — a DIY popular music heritage institution run exclusively by volunteers, most of whom are older adults and retirees — as a case study, we explore how third place can manifest in such sites of serious leisure. Drawing on interview data, we discuss volunteers’ experiences of the AJM in relation to its sociality and affective atmosphere and the role this institution plays in their lives. In doing so, we analyse the characteristics which contribute to DIY heritage institutions as spaces for caring, community, and wellbeing.