Eastern European migrants make up about 1.6% of the registered working population of Berkshire four years after EU expansion, research suggests.
The highest number is in Slough, where estimates show 3.2% of registered workers between 2004 and 2007 came from countries that joined the EU in 2004.
The government figures do not account for EU migrants who have returned home or who are not registered to work.
The research was conducted by The Institute for Public Policy Research.
The report marks the fourth anniversary of the enlargement of the EU in May 2004 and spans 2004 to 2007.
One of its authors, Danny Sriskandarajah, said migrants made a valuable contribution to the economy.
The total number of Eastern European migrants who registered to work in Berkshire between 2004 and 2007 was 13,315, out of a total estimated population of 815,900, according to the report.
In Slough, 3,835 migrants registered to work out of a total estimated population in the borough of 119,500.
'Settled more widely'
The town has one of the highest percentages of Eastern European workers in the UK - ranking at 20 out of 434 local authorities nationwide, the figures say.
Overall, the findings suggest Eastern European nationals have settled more widely throughout the UK than has happened during previous waves of migration.
Poles are now the largest foreign national group in the UK.
The research, released to the BBC, looked at migrants who came from eight countries that joined the European Union in May 2004 - Poland, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Slovakia and Slovenia.
It also included migrants from Romania and Bulgaria, which joined the EU in 2007.