Lawrence Lader, 86, an abortion rights activist who wrote an influential 1966 book on the history of the procedure and started a laboratory in suburban New York to manufacture the French abortion pill RU-486, died of colon cancer May 7 at his home in New York.

For 40 years, Mr. Lader was a clarion voice on behalf of women seeking abortions and for ensuring that the procedure was safe, legal and available. One of his books, titled simply "Abortion" (1966), was cited eight times in the U.S. Supreme Court's 1973 Roe v. Wade decision.

He was one of the founders of what is now known as NARAL-Pro Choice America. He left that group 30 years ago to start Abortion Rights Mobilization, and through it set up a secret laboratory to copy RU-486, or mifepristone, for distribution by clinical researchers because its European makers declined to enter the U.S. market.

"At times we have to be reminded of the history, and even today his books and work are relevant to the fight for reproductive rights and freedom," said NARAL President Nancy Keenan, who noted that 16 states currently are considering legislation that would allow pharmacists or pharmacies to refuse to fill birth-control prescriptions.

Described as the father of the abortion-rights movement by feminist Betty Friedan, Mr. Lader was an uncompromising advocate of a woman's right to choose whether to have an abortion. But after years of debating abortion opponents on radio and television, he ultimately refused to appear with them, his wife said, and he discarded the reams of hate mail that opponents sent to his home.

Mr. Lader was born in New York City and graduated from Harvard University in 1941. During World War II, he served in the Army, and his dispatches from the Pacific theater ran in the New Yorker. He was a magazine foreign correspondent during the Arab-Israeli War in the late 1940s and a contributing editor for Esquire. He ran unsuccessfully for New York state representative in 1948 on the radical American Labor Party ticket.

Although he was a successful writer for Look, Life, the Saturday Evening Post, Collier's and Reader's Digest, Mr. Lader itched for meatier topics than magazine stories.

He first addressed reproductive issues while writing a 1955 biography of birth-control pioneer Margaret Sanger. Sanger was anti-abortion and argued that birth control could solve the problem of unwanted pregnancies, but Mr. Lader believed that medical advances since she formed her opinions had made abortions safer. He came to believe "a woman had to be able to control her own fertility," he told the Los Angeles Times in 1995. While researching Sanger, he also realized that there had been no serious book or article written on abortion.

He tried repeatedly to sell a history of abortion as a magazine article, and an article appeared in 1965 in the New York Times Magazine. By the time his book was published in 1966, Mr. Lader said he had received hundreds of letters and telegrams from women seeking names of doctors willing to provide abortions.

"And I decided, in a flash of a second, All right, I've shot my mouth off, I will become an activist," he is quoted as saying in Cynthia Gorney's book "Articles of Faith: A Frontline History of the Abortion Wars" (1998). "I said, 'I will help women. If they write or phone me, I will get them to medical help.' "

After the U.S. Supreme Court expanded individual rights to privacy in matters of sexuality and family planning in the 1965 case of Griswold v. Connecticut, Mr. Lader's book topic suddenly had news value. He eventually published 10 books, all but the first two on abortion.

Impatient with the pace of change, he and others launched the National Association for the Repeal of Abortion Laws in 1969. In 1976, he left the group to form the smaller, more confrontational ARM, which sued anti-abortion activists under anti-terrorism laws. He sued the IRS for allowing tax exemptions to the Catholic Church, which opposes abortion. And, after Roussel-Uclaf refused to sell its RU-486 in the United States, and the government prevented activists from importing it, Mr. Lader set up a lab in Westchester County, N.Y., to manufacture the abortifacient from published patents and provide it to researchers.

After years of battles, Roussel-Uclaf allowed a U.S. firm to manufacture the drug, and the Food and Drug Administration approved its sale. RU-486, which terminates existing pregnancies, has lately been overshadowed by public interest in preventive "morning after" pills, commercially known as Preven or Plan B.

Mr. Lader, named the Feminist Majority's Feminist of the Year in 1992 for his efforts on RU-486, was still active in the abortion rights field. Earlier this year, he bought newspaper ads in South Dakota decrying that state's law banning nearly all abortions.

His marriage to Jean McInnis ended in divorce.

Survivors include his wife of 44 years, Joan Summers Lader of New York; and a daughter, Wendy Summers Lader of New York.