The issues of immigration and integration are at the forefront of contemporary politics. Yet debates over foreign workers and the desirability of their incorporation into European and American societies too often are discussed without a sense of history. McCook's examination questions static assumptions about race and white immigrant assimilation a hundred years ago, highlighting how the Polish immigrant experience is relevant to present-day immigration debates on both sides of the Atlantic. Further, his research shows the complexity of attitudes toward immigration in Germany and the United States, challenging historical myths surrounding German national identity and the American "melting pot."

In a comparative study of Polish migrants who settled in the Ruhr Valley and northeastern Pennsylvania, McCook shows that in both regions, Poles become active citizens within their host societies through engagement in social conflict within the public sphere to defend their ethnic, class, gender, and religious interests. While adapting to the Ruhr and northeastern Pennsylvania, Poles simultaneously retained strong bonds with Poland, through remittances, the exchange of letters, newspapers, and frequent return migration. In this analysis of migration in a globalizing world, McCook highlights the multifaceted ways in which immigrants integrate into society, focusing in particular on how Poles created and utilized transnational spaces to mobilize and attain authentic and more permanent identities grounded in newer broadly conceived notions of citizenship.