Digitalisation has given rise to concerns about the future effectiveness of older adult grassroots organisations in enabling group-based participation in later life. Despite this, these organisations and their potential role in securing a just digital transition has featured in neither research debates nor policy and innovation agendas. It is essential that this absence is addressed to ensure future citizenship rights across civic, social and political spheres within digitalising ageing societies. The aim of this article is to explore the impact of digital transformations on the capacity of older adult grassroots organisations to support group-based multifaceted engagement in later life. Focusing on an Irish national voluntary membership-based organisation, and its network of local groups, this analysis draws on data from a multi-level mixed-methods study design. Data collection involved: European expert interviews (n = 4); social media analysis (X); organisational-level interviews (n = 11); an older adult member survey (n = 464); follow-up lifecourse interviews (n = 40); and a Translational Forum involving participants from all research strands to validate findings and agree key messages (n = 13). The analysis demonstrates the transitional nature of digital communication for these groups, and the need to and difficulties in addressing the diverse preferences and digital literacies of grassroots membership. The analysis also shows that the most significant challenges are systemic and structural in nature. An assets-based, capability-orientated approach that is supported by state-level leadership and resourcing is required to equip ageing societies for an equitable digital transition.