The nation's preeminent seniors group, AARP, has put the weight of its 40 million members behind health-care reform, saying many of the proposals will lower costs and increase the quality of care for older Americans.

But not advertised in this lobbying campaign have been the group's substantial earnings from insurance royalties and the potential benefits that could come its way from many of the reform proposals.

The group and its subsidiaries collected more than $650 million in royalties and other fees last year from the sale of insurance policies, credit cards and other products that carry the AARP name, accounting for the majority of its $1.14 billion in revenue, according to federal tax records. It does not directly sell insurance policies but lends its name to plans in...