Interest in migrant social networks and social capital has grown substantially over the past several decades. The relationship between “host” and “migrant” communities remains central to these scholarly debates. Recently urbanized cities in Africa, which include large numbers of “native-born” or internal migrants, challenge basic presumptions about host/migrant distinctions informing many of these discussions. Using comparable survey data from Johannesburg, Maputo, and Nairobi, we examine 1) the nature of social connectedness in terms of residence and nativity characteristics; and 2) the relationship between residence and nativity characteristics and three measures of trust within and across communities. Our findings suggest that the host/migrant distinction may not be particularly revealing in African cities where domestic mobility, social fragmentation and the absence of bridging institutions result in relatively low levels of trust both within and across communities. These findings underscore the need for new concepts to study “communities of strangers” and how people strategize their social mobility in urban contexts.