For years the technology sector has been considered the most dynamic, promising and globally envied industry in the United States. It escaped the recession relatively unscathed, and profits this year have been soaring.

"I apply for everything I can find, but there are just not that many jobs,"� said Rosamaria Carbonell Mann, a software engineer.

But as the nation struggles to put people back to work, even high-tech companies have been slow to hire, a sign of just how difficult it will be to address persistently high joblessness. While the labor report released last week showing August figures provided mildly positive news on private-sector hiring, the unemployment rate was 9.6 percent.

The disappointing...