This paper examines the causal effect of the possibility to vote on foreigners' propensity to naturalise - a key indicator of successful integration. Based on Swedish administrative data and an institutional setting producing a quasi-random assignment of the eligibility to vote, we find that the overall effect depends on the composition of the migrant population. For immigrants from places with poor living conditions, we observe that the experience of non-citizen voting rights substantially increases their propensity to naturalise. However, for those coming from places with a high standard of living, the same experience reduces it. Both reactions clearly reveal that individuals assign a positive value to formal democratic participation rights. While the behaviour of the former group is likely dominated by the motivational force inherent in the possibility to participate, the behaviour of the latter group reflects the devaluation of formal citizenship if it is decoupled from democratic rights.