Abstract Starting from the empirical evidence that minorities are more likely to work on flexible contracts, we investigated the existence of an ethnic gap in flexible contracts between the native Dutch population and sub‐Saharan African immigrants between 2006 and 2012. The migrant group is taken as a test case of ‘outsiders’. This study found, quite surprisingly and contrary to what several theories predict, that the expected ethnic gap in job status between the two groups disappeared in the 6 years between 2006 and 2012. Many sub‐Saharan Africans successfully transformed their flexible contracts into permanent ones, catching up with the native Dutch by 2012. The analysis of the statutory provisions showed that the workforce numerical composition in the cleaning industry was important for the inclusiveness of sub‐Saharan immigrants. This numerical compositional effect was facilitated by the collective agreements negotiated by trade unions, agreements that were extended to temp workers. Sub‐Saharan Africans, overrepresented in the cleaning industry, have benefited disproportionally from the settled agreements. We thus conclude that trade unions can improve the inclusion of migrants not only by explicitly focusing on migrant representation but also by targeting sectors with an overrepresentation of migrants.