A new report on the community group Acorn by the nonpartisan Congressional Research Service has found no evidence of fraudulent voting or of violations of federal financing rules by the group in the past five years.

Representative John Conyers Jr., Democrat of Michigan and chairman of the House Judiciary Committee, requested the report along with Representative Barney Frank, Democrat of Massachusetts. Mr. Conyers released the report on Tuesday.

Acorn, which stands for the Association of Community Organizations for Reform Now, has drawn fire from conservative activists who have accused it of conducting fraudulent voter registration drives in poor neighborhoods, adding imaginary voters like Mickey Mouse to the rolls. The report by the research service, an arm of the Library of Congress, said, however, that a search using the Nexis news database “did not identify any reported instances of such individuals attempting to vote at the polls.”

Hans A. von Spakovsky, a former Federal Election Commission member under President George W. Bush, said the new report could not resolve the voting fraud issue, since “no one is ever going to know it unless somebody takes the voter registration list and checks each person who is registered to make sure they are a real person.”