The study was conducted by the Corporation for National and Community Service, a federal agency whose programs include Senior Corps and AmeriCorps, and tracked volunteer efforts for all 50 states and the District of Columbia.

Some 48 percent of Utah residents 16 and older served as volunteers between 2003 and 2005. Nebraska was second with 42.8 percent, followed by Minnesota with 40.7 percent, Iowa with 39.2 percent and Alaska with 38.9 percent.

The report said that more than 65.4 million Americans performed service of some kind in 2005 alone, compared to 59.8 million in 2002.

''Overall we're doing terrific,'' CNCS Chief Executive David Eisner said in a telephone interview. ''We seem to be having a renaissance of civic engagement.''

Eisner credits the increase to a call for American service by President Bush after the Sept. 11, 2001, attacks and to a sense of duty stirred along the Gulf Coast by hurricane destruction in recent years.

The survey tracked the volunteer rates of participating individuals, their ages, hours served, gender, race and ethnicity. It also looked at where people volunteered and what types of activities they performed. Data for the survey were collected by the Bureau of Labor Statistics and the U.S. Census Bureau.

Nationally, the study found that women volunteered more often than men, married people did more volunteer work, and blacks volunteered more frequently than any other nonwhite group. The most committed age group was Americans 35-44 years old.

Most Americans - 34.8 percent - said they volunteered primarily through religious organizations, with 26.2 percent of volunteers giving time to educational or youth-related organizations.

More than 35 percent said they volunteered as coaches, referees, tutors or mentors, followed by fundraising at 29.7 percent and collection, preparation or distribution of foods at 26.3 percent.

''We need volunteering to be as much a part of people's lives as their work, their families and their social time,'' Eisner said.

Utah topped the charts in nearly every category. In addition to having the highest percentage of volunteers, its residents gave the highest number of service hours, 96, compared to the national average of 50 hours.

The survey found more than 63 percent of Utah residents linked their volunteer service in 2003-2005 to religious organizations; nationally, 34.8 percent cited religion in 2005. It is estimated that at least 70 percent of Utah residents are members of the Church of Jesus Christ of Latter-day Saints, which stresses helping the needy as part of its mission.

''It would seem that the prevalence of the faith-based community in Utah contributes to it being No. 1,'' Eisner said. But he noted that Vermont also has a very high volunteering rate (38.1 percent), along with one of the lowest religious participation rates.

Those over 65 gave the most time, with 51.8 percent serving as volunteers. But young Utah residents also took top honors, with 45.4 percent of those ages 16-24 volunteering and 62.9 percent of college students performing service work.