This study explored the complex relationships between immigration, volunteering, and life-long learning among older adults. It investigated adult teaching and learning and active ageing from the perspective of immigrant volunteer instructors of English as additional language. Using a grounded theory method (GTM), comprising a combination of narrative and participatory approaches, we investigated the context, motivation, experiences, and effects of two Chinese immigrant volunteers teaching English in Chinese communities in the Greater Toronto Area (GTA) in Canada. We aimed to understand the complex mechanisms and implications of adult teaching and learning as part of active ageing. Findings demonstrated that the policy model of active ageing as defined by the World Health Organization was reflected in lay views and actions. Immigrant volunteers participated in active ageing by teaching English. They also promoted active ageing among their learners. The volunteers' bottom-up approach, with its innovative self-designed curriculum and learner-centred pedagogy, seemed to meet the practical needs of their learners, while promoting their active ageing in key areas of health, security, integration, and participation.