The estimated figure of students taught at home has grown 29 percent since 1999, according to the National Center for Education Statistics, part of the Education Department.
In surveys, parents offered two main reasons for choosing home schooling: 31 percent cited concerns about the environment of regular schools, and 30 percent wanted the flexibility to teach religious or moral lessons. Third, at 16 percent, was dissatisfaction with academic instruction at other schools.
The figures were released Tuesday.
"There's potential for massive growth," said Ian Slatter, spokesman for the National Center for Home Education, which promotes home schooling and tracks laws that govern it.
"Home schooling is just getting started," he said. "We've gotten through the barriers of questioning the academic ability of home schools, now that we have a sizable number of graduates who are not socially isolated or awkward — they are good, high-quality citizens. We're getting that mainstream recognition and challenging the way education has been done."
In perspective, the 1.1 million home-schooled students accounts for a small part — 2.2 percent — of the school-age population in the United States, young people aged five through 17.
Slatter said the new figures accurately reflect the growth of home schooling but underestimate the number of children involved; his group says it is 2 million.
In the government's view, home schooling means students who spend at least part of their education at home and no more than 25 hours a week in public or private schools. Overall, more than four out of five home-schooled students spend no time at traditional schools.
A separate federal report showed a rising number of teenagers are skipping school for fear of getting hurt, even though reported school violence is down.
That sense of anxiety — fueled by terrorism warnings, high-profile school shootings and a desire to keep children out of harm's way — probably has helped home schooling grow, said Ted Feinberg, assistant executive director of the National Association of School Psychologists.
Home schooling presents several questions that must be considered, he said. Among them: Do parents with no formal training as teachers know how to handle a variety of subjects or to tailor instruction for children of different ages? Do students get the same materials they would have at schools, from books to science labs? Are families with two working parents prepared to go to a single income so that one parent can teach at home?
Also, Feinberg said, parents must consider whether their children will emerge from home schooling with limited exposure to other children and various cultures. More federal research is needed to help resolve such questions about home schooling, he said.
"At some point, children are going to have to interact with the rest of the world," he said. "If they haven't had the opportunity to build their emotional muscles so they have that capacity to interact, how effective are they going to be outside their cloistered environment?"