Most studies on neighbourhood change attribute a key role to mobility in social upgrading and downgrading patterns, while incumbent processes—i.e. changes in the socioeconomic status of non-migrants—are often ignored. This paper explores the relationship between mobility and neighbourhood change by examining income developments of in-migrants, out-migrants and non-migrants of neighbourhoods in three Dutch cities. The paper demonstrates that in- and out-migration are not the only processes at work and that changes in the socioeconomic status of non-migrants are of importance too. Within upgrading neighbourhoods, incumbent processes of non-migrants seem to be an important driver of upgrading. Furthermore, although in-migrants have relatively low incomes when moving in, they experience strong income gains in the years after in-migrating. The contribution of out-migrants to upgrading is mixed. In line with previous studies, migration reinforces downgrading processes, although at the same time, incumbent processes of non-migrants impede downgrading.