Resources on European Citizens and Third Country Nationals
Whilst some 14.5 million EU citizens live in another Member State there are 21 million Third Country Nationals (TCNs).
EU policies have reduced the gap between the two groups, at least on paper (Directive 2003/109/CE on longstanding TCNs).
The best sources on acquisition of nationality of a Member State as the route to European citizenship is the EUDO website.
CEPS has useful material on the integration of migrant workers in the EU.