Updated

The number of Americans who volunteer to mentor students, beautify neighborhoods and pitch in after disasters is at a 30-year high, fueled in part by a boom in teen participation, a new study says.

The report by the Corporation for National and Community Service tracked volunteer rates since 1974. It found that more than 1 in 4 adults — or 27 percent — currently give time to their communities, a jump from a low of 20.4 percent recorded in 1989.

Teens aged 16 to 19 saw the biggest jump, with 28.4 percent volunteering compared to just 13.4 percent in 1989.

Service among mid-life adults (ages 45 to 64) and senior citizens (ages 65 and over) also remained strong at 30 percent and 23.5 percent, respectively. The study, which is set to be released Monday, credits higher education levels, delayed childbearing and longer life expectancy.

"We are encouraged that emerging studies consistently show increased volunteering by young Americans. If supported properly, we may be on the cusp of a new civic generation," said Robert T. Grimm, director of research and policy development at the corporation.

The group, which promotes volunteering through federal programs such as Senior Corps, AmeriCorps and Learn and Serve America, attributed increased volunteering among youths to a rise in service-learning programs in schools and colleges that combine classroom study with community work.

Increased altruism in response to disasters such as the Sept. 11, 2001, terror attacks also have played a role, according to Grimm.

The report analyzed volunteering rates in 1974, 1989 and 2003-2005, using information collected by the U.S. Census Bureau and the Bureau of Labor Statistics.

It also found:

— More adult volunteers serve through religious organizations (35.5 percent) than through other types of groups such as education (24.6 percent).

— Baby boomers are volunteering in greater numbers, accounting for a 37 percent increase in participation among mid-life adults since 1989.

— Older adults tend to volunteer more intensively, serving 100 or more hours a year. In contrast, most teens (67.9 percent) contribute more sporadically, amounting to 99 or fewer hours a year.

"America needs more volunteers to mentor and tutor at-risk youth, care for seniors, respond to disasters and meet a wide range of other critical needs," said David Eisner, CEO of the organization.