White and Asian employees, regardless of pay, are far more likely to participate in 401(k) plans and to make bigger plan contributions than African-American and Hispanic employees, according to a study released Tuesday.

Among those employees earning between $30,000 and $59,999, 75% of African-American and Hispanic employees participated in their employers' 401(k) plans. That compares with an average participation rate of 84% for Asian employees and 80% for white employees, according to a study conducted by Hewitt Associates Inc. in Lincolnshire, Ill., and Ariel Education Initiative, a nonprofit affiliate of Ariel Investments, a Chicago-based mutual fund provider.

Participation rates also were linked to racial and ethnic backgrounds at higher income levels. For example, participation rates for those earning between $60,000 and $89,999 averaged 83% for African-American employees and 85% for Hispanic employees. The participation rate averaged 92% for Asian employees and 88% for white employees in the $60,000 through $89,999 pay range.

At the highest income range, though, the differences in the participation rate were much smaller. For those with earnings of at least $120,000, the participation rate for Asian employees averaged 94%, compared with 92% for whites, 91% for African-American employees and 90% for Hispanic employees.

How much employees contributed to 401(k) plans also was directly tied to their racial and ethnic backgrounds. For example, on average, African-American employees earning between $30,000 and $59,999 deferred 5.9% of pay and Hispanic employees deferred 6.1% of pay to their 401(k) plans. By contrast, Asian employees in the same pay range deferred an average of 8.4% of pay, while whites deferred an average of 7.1% of pay.

These racial and ethnic differences exist even at the highest income levels. For example, Asian employees earning at least $120,000 a year, deferred an average of 12.1% of pay to their 401(k) plans, while white employees deferred an average of 10.4% of pay. That compares with an average deferral rate of 9.7% for Hispanic employees and 9.2% for African-American employees.

The study also found that Asian and white employees, on average, take fewer hardship withdrawals and loans from 401(k) plans than African-American and Hispanic employees.

The study didn't attempt to analyze why participation and contribution are higher for Asian and white employees compared with African-American and Hispanic employees. Still, those differences need to be addressed “if retirement security is to be a reality for all Americans,” said Mellody Hobson, president of Ariel Investments, in a statement.

“A Study of 401(k) Savings Disparities Across Racial and Ethnic Groups—The Ariel/Hewitt Study,” funded by the Rockefeller Foundation, is based on 401(k) plan information—through Dec. 31, 2007—for 3 million employees working at 57 large companies.

Summaries of the study are available at www.hewittassociates.com and www.arielinvestments.com.