This study demonstrates that mobility was a constitutive factor in late medieval society. At the same time, however, trans-Alpine immigrants found it difficult to maintain contact with their places of origin, which encouraged their acculturation. A micro-study draws on results from a tableau of Italian host towns to discuss in detail immigration phases, migrant groups, and inclusion and exclusion factors with specific reference to the town of Treviso, situated in the catchment area of Venice. The conclusion is that the ´strangers from the north` were no more 'alien' than people moving to the town from other places in Italy itself.