The main purpose of this article is to analyse Barcelona’s mainstreaming approach to intercultural policy from the beginning of its immigration process. My key questions are threefold: (a) why was Barcelona attracted by the intercultural approach so early in 1997? (b) how can we understand the consolidation of interculturalism? and (c) how can its successful permanent endurance (16 years) be explained, given different migratory contexts/political governments? I will argue that Barcelona’s status as a key player within the multi-level system of Catalan and Spanish governance has been a favourable key factor.

I will first feature the mainstreaming approach, and then defend the argument that the vertical dimension has helped to strengthen the legitimacy of the horizontal dimension, as it has provided a favourable environment in which interculturalism can flourish. I conclude by highlighting the fact that the analysis of Barcelona helps to provide new meanings for the multi-level governance debate in diverse European cities.

Points for practitioners

Multi-level governance and cities networks influence the policy design and the consolidation of cities’ diversity policies. There is an assumed link for cities between intercultural policies and the mainstreaming approach in diversity policies. The relationship between the vertical and horizontal dimensions of multi-level governance plays a key role in promoting a favourable environment for these policies to thrive.