Despite the tax savings and long-term benefits of stashing pre-tax income in retirement plans, the majority of workers fail to take advantage of employer-sponsored programs, such as 401(k) accounts, the group reported.
The 39.4 percent participation rate in 2012 was a slight decrease from a 39.7 percent rate a year earlier, the group said.
Government employees were much more likely to participate, with 71.5 percent contributing to their retirement plans, the report said.
Those less likely to participate were younger, nonwhite or unmarried or had lower education levels, the report said. Also, those with lower income levels or health problems were less likely to participate.
Women participated at lower rates than men, the report said. Latinos born outside the United States had "substantially lower" levels of participation, the report said.
Financial advisors have long counseled workers to contribute to their 401(k) accounts because many employers no longer offer traditional pensions and Social Security will not provide enough income for most people during retirement.
One of the most significant advantages of 401(k) accounts is that workers do not have to pay taxes on the contributions until the funds are withdrawn. This allows money that would have been paid in taxes to generate interest and investment income that can compound for decades.