Concrete indicators can be specified for these areas. However, the choice of reference values poses a problem, since immigrants and natives are heterogeneous and structurally different population groups. For example, if one compares the labour market situation of immigrants with a higher proportion of low-skilled with that of all natives, one ultimately expects them to perform better than people with the same level of education. If, on the other hand, they are only compared with the latter, successful integration may be stated even if the two groups differ greatly. Another challenge is the definition of the target groups of integration, which should form a unit clearly delimited from the natives. This does not apply to the population with a migration background as a whole that is often considered in the relevant research. Rather, many people of the second generation are natives in their own perception and in the perception of others and have hardly any points of contact to milieus shaped by migrants.

Against this background, the Socio-Economic Panel (SOEP) was used to evaluate the various aspects of the state of integration for the large immigrant groups in Germany that can be depicted with the available case numbers. Although further integration steps are still necessary in most cases, these draw a positive picture altogether. In particular, the situation has improved significantly in many cases in recent years and the children of the second generation born in Germany generally reach a much higher level than the first-generation immigrants themselves. In the case of second-generation immigrants from the new EU member states, it can even be said that the integration process has already been fully completed. Second-generation immigrants from Southern Europe and immigrants from Western Europe also achieve very good results in most areas. However, they see themselves comparatively rarely as Germans, which could be related to the common European identity. Nevertheless, integration policy must be further strengthened against the background of the increasing importance of immigration for growth and prosperity in Germany due to demographic change. In order to do this effectively and efficiently, the studies on the integration process, which are already provided in very high quality by the Expert Council on Migration and Integration, for example, must be further improved.