Because of its growing Hispanic population, Boston has been required since 1992 to provide all election materials in Spanish, but the lawsuit alleges the city's elections Web site and notices posted in polling places were only in English.
"Despite having had an unequivocal obligation for 13 years to provide Spanish language information to voters who need it ... the city of Boston has consistently fallen well short of the mark," Bradley J. Schlozman, acting assistant attorney general, said in a statement Friday.
The city also has failed to recruit a pool of bilingual poll workers to help voters who speak Spanish, Chinese or Vietnamese, the suit alleged.
City officials said they already provide ballots in English and Spanish. They said the Justice Department was intent on gaining news coverage rather than solving perceived problems.
"It is a totally unsubstantiated complaint," said Merita Hopkins, the city's top attorney and chief of staff to Mayor Thomas Menino. "They've insisted that they're going to sue us. They're going around the country and doing this."
A check Friday night of the Web site showed there was a link to a Spanish language version.
The lawsuit, which names Menino, city councilors and elections officials as defendants, asks the court to force Boston to comply with the law and to authorize the appointment of federal examiners for elections in Boston through 2007.
Justice Department officials said the lawsuit was part of a national initiative in several states. Complaints also have been filed in California, Florida, Mississippi, New York, Pennsylvania and Washington.