International policy emphasises the importance of slum dwellers' rights of access to cities and their social inclusion. Legalisation of land holdings in informal settlements is one way of enacting this policy. However, this measure favours house owners over the large proportion of tenants renting rooms in private houses in informal settlements in many cities in the global South. Rental housing is neglected by many governments. What role does the form of house tenure play in other processes of social inclusion in informal settlements? This article examines one of many forms of social inclusion: participation of tenants and owners in rotating savings groups and help groups in two areas in Mwanza city, Tanzania. The results indicate that both tenants and owners participate in groups, which are based not only on the geographical area of residence but on work, ethnicity and religion. The study also indicates that not all groups accept tenants as members, because of their high mobility.