A student who left the Landon School in Bethesda after he was involved in cheating on the SAT filed a lawsuit in Montgomery County Circuit Court on Thursday, claiming the all-boys private school improperly forced him to withdraw while letting other offenders stay.

William Anderson, 17, of Chevy Chase acknowledges that he cheated during the exam given Oct. 12. A classmate couldn't keep track of answers another boy was trying to tell him, the suit says, so Anderson typed them into his calculator and passed it over, without using the answers himself.

The suit, filed by Anderson and his parents, Byron and Mary Anderson, alleges that of the 10 boys who cheated, eight suffered less for greater malfeasance: not only copying answers but also doing portions of each other's tests and smuggling a dictionary into the testing room at Holton-Arms, the Bethesda all-girls school where they took the exam.

Rumors about the cheating swirled around Landon for a month. In mid-November, eight boys, not including Anderson and the student he passed the answers to, came forward and confessed, the suit says. They were suspended for the rest of the semester (though they were allowed to take exams), assigned community service on campus and had some privileges rescinded.

"While the boys' infraction could clearly warrant separation from the School," Headmaster Damon F. Bradley wrote in a letter Nov. 26 to Landon students and parents, "the fact that they came forward of their own accord persuaded the [Student] Council to stop short of recommending the most severe penalty."

Anderson's suit alleges that the eight came forward only because they were told that doing so would mitigate their punishment, and that they were "tipped off" to this because some played on the school's "powerhouse" lacrosse team.

When confronted, Anderson and his classmate admitted their transgressions; they were given the chance to withdraw from Landon or face expulsion.

The suit alleges that Anderson was excluded from the discussions about coming forward not because his cheating was less severe or because his SAT score did not increase suspiciously, but rather because he and his classmate were "less-favored."

Bradley declined to discuss the suit, saying, "This is one place where I don't think I should comment."

Educational Testing Service, which administers the SAT, investigated the incident, found irregularities and threw out the scores of the Landon students and others who took the test that day at Holton-Arms.

The suit contends that cheating on the SAT does not violate the school's honor code, which defines cheating as unauthorized help on "a written assignment" and specifies conduct only at Landon School.

The Andersons are asking for $1 million in punitive damages for defamation, which the suit claims occurred when Bradley, talking to a Washington Post reporter, failed to distinguish William Anderson's conduct from that of the other boys; did not disclose that his SAT score "had only risen 20 points," compared with large gains made by other offenders; and said that past expulsions "have been limited to serious, repeat offenders." All the boys had previously had spotless records, Bradley said in his November letter.

The Andersons also seek $100,000 to compensate for $13,120 in tuition payments, "loss of invaluable childhood friendships with boys he has been going to school with for nine years, and loss to his reputation."

Metro researcher Bobbye Pratt contributed to this report.