Rapid urbanisation in sub-Saharan Africa is believed to have weakened the traditional family ties which sustained older people in the past, but there is little empirical evidence about how older people today perceive their ageing experience in sub-Saharan Africa. The international gerontology literature demonstrates that, apart from financial wellbeing and health status, religious and secular forms of social involvement are key predictors of life satisfaction in older ages. No formal analysis, however, exists on the effects of religious and non-religious social involvement on the subjective wellbeing of older people in sub-Saharan nations. This study sought to fill this gap by examining the relationship between religious identity, religiosity, and secular social engagement using survey data from a sample of 2,524 men and women aged 50 or more years living in informal settlements of Nairobi City. We found significant differences in life satisfaction between Moslems, Catholics and non-Catholic Christians. Secular social support, personal sociability and community participation had positive effects on subjective wellbeing. In this context, we also observed that next to health status, the social involvement of older people was very important for life satisfaction.