DROGHEDA, Ireland — Brian and Rosie Condra grew up poor. But as prosperity washed over Ireland in the first decade of the 21st century, they managed to buy a modest house, start saving for their children’s future and, for once, do more than simply make ends meet.

“We were on the up and up,” Mr. Condra said.

The Condras are among hundreds of thousands of Irish who, over the last few years, finally started to catch up with and even surpass many of their European neighbors. But now, after a stunning plunge fueled by a disastrous banking collapse, the economy has fallen back to where it was in 2005, before a housing bubble stoked a growth frenzy.

“The last several years of growth in Ireland have effectively been wiped out,” said Constantin Gurdgiev, an economist and lecturer at Trinity College in Dublin.

For many people in Ireland, it is as if the boom never happened. And some of those who floated up during the good times now see themselves slipping even further behind.