Foreigners have increasingly influenced the process of business start-ups in both Germany and North Rhine-Westphalia between 2004 and 2014. Foreign founders have played a particularly important role in the commercial sector. Differentiating analyses based on business advertisement statistics show that the start-up boom among foreigners is exclusively attributable to citizens of the eastern and central European EU accession states of 2004 and 2007. A decline in the number of commercial start-ups was observed among other foreigners during the period under review, as well as among Germans. Some of the start-ups by foreigners have a different focus of activity and, on average, a lower economic substance than that of German founders. These differences are in turn largely attributable to the citizens of the above-mentioned EU accession states, whose share in commercial start-ups has been declining since 2014.