Eunan King, an economist at NCB Stockbrokers in Dublin, has long argued that a rising population — more workers and more consumers — will help sustain Ireland’s remarkable economic renaissance of the past dozen years.

Image Immigration is swelling Irelands population. Pastor Lawrence Eferetin, a Nigerian immigrant, baptized a baby born in Dublin. Credit... Ross McDonnell for The New York Times

The largest increases in immigration since 2002 have been from Poland, Lithuania and Nigeria. The latest census showed 63,276 Poles living permanently in Ireland, up from 2,124 four years earlier. In some small districts in Dublin, Limerick and Cork, the census showed, 52 percent of residents were non-Irish, said Aidan Punch, a senior census statistician.

Ireland permits all residents, not just Irish citizens, to cast ballots in local elections. That has helped immigrants win seats in local councils. The mayor of the midlands town of Portlaoise, Rotimi Adebari, is from Nigeria.

To encourage assimilation, the government recently named a minister for integration, Conor Lenihan. The department was organized, Mr. Lenihan said in an interview, to show Ireland’s commitment to share and develop its new wealth with new arrivals. “We have chosen a midpoint between the U.S. and Europe in terms of our economic success,” he said. “I think we can choose a midpoint in integration as well.”

Mr. Lenihan said his department would investigate ways to provide extensive language classes for adult immigrants and to increase training for unskilled local Irish workers.

But immigrants’ representatives say the government needs to do more.

“Ireland should be taking a lead in Europe,” said Jean-Pierre Eyanga Ekumeloko, a naturalized Irish citizen from Congo and a co-founder of Integrating Ireland, an independent support group for immigrants.

Mr. Ekumeloko said the Irish prime minister should lay out a plan for welcoming and integrating immigrants. He said many were working jobs for which they were overqualified. “A lot of things have changed in interactions between the Irish community and immigrants,” he said, adding that in the past he had heard racist remarks. “Things have changed very positively. Now Irish people know Africans.”