The curtain falls on a bevy of near-naked dancers in feathered headdresses, and Adir Rafael Pires glides into action. As a set-changer at the Lido, the racy cabaret on Paris' Champs-Elysees, Pires could not be farther from his desert birthplace: Cape Verde, a rocky, drought-stricken archipelago off West Africa's coast. But the door that allowed Pires to make France his home may now be closing. France, like other European countries, is taking a harder look at the immigrants it lets in. The drive toward "selective" immigration is inspired by electoral politics, by fears that some immigrants are not integrating and...