Bob Moses, a towering but self-effacing leader of the civil rights movement who, after enduring beatings and jailings to register Black voters in Mississippi in the 1960s, picked up the civil rights torch 20 years later by founding the Algebra Project, a math education initiative aimed at rural and inner-city students, died July 25 at his home in Hollywood, Fla. He was 86.

Ben Moynihan, the director of operations for the Algebra Project, confirmed the death to the Associated Press.

Bespectacled, owlish and bearing a master’s degree in philosophy from Harvard, Mr. Moses was an unlikely front-line activist — much less an obvious candidate to quit his comfortable prep-school teaching job in the Bronx in 1960 and immerse himself in the most violently segregationist precincts of Mississippi.

A janitor’s son raised in New York public housing, he showed precocious talent for academic fields involving logic, especially mathematics and philosophy. He found kinship with Quaker friends in college, and he submerged himself in the writings of Albert Camus, the French-Algerian Nobel laureate whose books explored universal questions of human existence and justice.

As the civil rights movement gained momentum, Mr. Moses felt at a certain intellectual remove. “Words are more powerful than munitions,” his early intellectual lodestar, Camus, once wrote. But a turning point for the 25-year-old Mr. Moses was reading news accounts of the nascent sit-in protests in the South. He studied the newspaper dispatches for weeks, mesmerized and finally ready to engage.

“Before, the Negro in the South had always looked on the defensive, cringing,” he once said. “This time they were taking the initiative. They were kids my age, and I knew this had something to do with my own life.”

Mentored by civil rights veterans Bayard Rustin and Ella Baker, he joined the Student Nonviolent Coordinating Committee (SNCC), sidestepped the sit-ins and initiated voter-registration drives instead as a more direct way to gain political power for Black Americans.

He chose rural southwest Mississippi, the most intransigent region of the state, as his target. There, in “freedom schools,” he taught African Americans how to register and pass the stringent voter literacy tests. Often working alone or with one or two SNCC organizers, he was repeatedly threatened by White mobs and law enforcement officials as he accompanied Black people to courthouse registration offices.

They were suspicious of the educated Black man from New York who seemed impervious to threats or brute force. In front of a courthouse in Liberty, Miss., in August 1961, where Mr. Moses was leading a few men to register, an assailant emerged from the crowd and smashed a knife handle on Mr. Moses’s head.

With blood dripping from his skull, Mr. Moses continued into the courthouse, only to find the registrar’s office closed. Mr. Moses, whose wound required eight stitches, pressed charges against Billy Jack Caston, the man who injured him. Caston, a cousin of the sheriff, was acquitted by an all-White jury on self-defense grounds, after claiming that Mr. Moses had brushed against his shoulder and assumed a threatening stance.

Mr. Moses remained in the thick of danger for four years. His office was burned. He was jailed at times and reported being shot at by White people in a passing car near Greenwood, Miss., in 1963.

In 1964, he helped organize the Mississippi Freedom Summer Project, bringing hundreds of White college student volunteers to help with the voter drive as a way to generate national publicity and pressure Congress to enforce Black voting rights. (President Lyndon B. Johnson signed the landmark Voting Rights Act the following year.)

That summer was also when the racially mixed Mississippi Freedom Democratic Party failed in a dramatic effort to unseat Mississippi’s regular all-White delegation to the Democratic National Convention in Atlantic City. It was a deep disappointment for Mr. Moses, one of the key architects of the challenge, especially when he saw White Northern liberals side with segregationists.

It had been an exhausting battle. And by the late 1960s, he was pulling away from SNCC, not only because of its increasing Black nationalist radicalism under leader Stokely Carmichael, but also because of his own shift in focus from civil rights to opposing the Vietnam War.

In 1966, he decamped for Canada after being denied conscientious-objector status by the U.S. draft system. He also spent years as a teacher in Africa with his wife before returning in 1977 after President Jimmy Carter granted amnesty to draft evaders. Mr. Moses soon began building his second enduring legacy, the Algebra Project.

Though less dramatic and harrowing than getting Black voters to the polls in Mississippi, the Algebra Project marked a pivotal shift in his civil rights vision from political to economic equality.

The project has instructed thousands of middle school students in what Mr. Moses called “math literacy” as a crucial steppingstone to college and employment, an often difficult process among underserved students.

Low math achievement among minority students is “the nation’s dirty secret,” he often told educators. He urged them to avoid the tendency to neglect the subject and instead help students escape their “serf-like communities” within high-tech society, just as sharecroppers earlier sought release from the serfdom of the plantation.

“Math literacy,” he said, “is a civil right. Just as Black people in Mississippi saw the vote as a tool to elevate them into the first class politically, math is the tool to elevate the young into the first class economically.”

His pedagogical method focused on bottom-up reliance on the initiative and will of students to spark their own enthusiasm and was similar to the grass-roots approach of his earlier voter-registration work.

That approach — in which he shunned personal leadership, prompting individual rank-and-file people to initiate actions and ideas — also caused him to clash with the more mainstream and hierarchical organizations in the civil rights movement.

“Moses pioneered an alternative style of leadership from the princely church leader that [the Rev. Martin Luther] King epitomized,” Pulitzer Prize-winning historian Taylor Branch told Mother Jones magazine in 2002. “. . . He is really the father of grass-roots organizing — not the Moses summoning his people on the mountaintop as King did but, ironically, the anti-Moses, going door to door, listening to people, letting them lead.”

David J. Garrow, also a civil rights historian and Pulitzer recipient, said of Mr. Moses in an interview for this obituary, “In personality and demeanor, he was more poet than politician.”

The Algebra Project relies on igniting enthusiasm among students by having them link common daily tasks to basic mathematical procedures, using schoolyard vernacular and helping one another with minimal teacher input. In the process, students learn to solve problems by converting concrete numerical values — distances walked, liquids measured — to abstract algebraic symbols.

Over the years, the project has served more than 40,000 students in hundreds of schools nationwide. Its students’ performance has generally exceeded that of other peer groups, and the project has won national awards and the praise of numerous academics.

Freeman A. Hrabowski III, a mathematician and president of the University of Maryland at Baltimore County, told the New York Times in 2001 that Mr. Moses’s Algebra Project was “an excellent way of connecting mathematics to life itself.”

A janitor's son

Robert Parris Moses was born in New York City’s Harlem neighborhood on Jan. 23, 1935. While his father was emotionally erratic and limited largely to janitorial work, there was a tradition of education in the family. His grandfather, William H. Moses, was a prominent Baptist minister, and an uncle was a college professor.

Urged by his father to seek a fuller education, Mr. Moses gained entrance to New York’s Stuyvesant High School for gifted students, where he scored in the middle of his class. But it was enough to win a scholarship in 1952 to Hamilton College, a small, virtually all-White liberal arts school in Upstate New York.

There, he sharpened his already established aptitude for mathematics and in 1956 majored with honors in philosophy. Drawing on his reading of Camus, he began developing concepts of pacifism, nonviolence and the use of power, especially in the context of race relations.

Attracted by friends to the Quaker tradition, he spent summers volunteering at Quaker-sponsored construction sites in Belgium, France and Japan.

In 1957, he obtained a master’s degree in philosophy at Harvard but interrupted his doctoral studies there when his mother died the next year. He returned to New York to be near his father, who suffered a mental collapse. Mr. Moses quickly found work teaching mathematics at the prestigious Horace Mann private school. After a few years, he joined SNCC and became its Mississippi field secretary.

His first marriage, to SNCC worker Dona Richards, ended in divorce. In Canada, living under an assumed name, he married Janet Jemmott, a former SNCC activist.

In 1968, they moved to Tanzania, in East Africa, where for eight years they taught secondary-school math and English. They had four children. A complete list of survivors was not immediately available.

After Carter’s blanket pardon, Mr. Moses and his wife settled in the Boston area. He resumed doctoral studies at Harvard in the philosophy of mathematics, and his wife entered medical school.

Appalled by his daughter Maisha’s poor grounding in grade-school math, he abandoned his doctoral work and founded the Algebra Project in 1982, winning a MacArthur Foundation “genius” grant to fund its first five years. By 2001, it was serving 10,000 students in 28 cities with a $2.5 million annual budget, expanding beyond that in following years.

With former SNCC worker Charles E. Cobb Jr., Mr. Moses co-wrote the book “Radical Equations: Math Literacy and Civil Rights” (2001), outlining the Algebra Project.

Friends described Mr. Moses as a quintessential loner, friendly but reserved, soft-spoken, reflective, equally unflappable in a crowded classroom in Boston or a hostile voter-registration office in backcountry Mississippi.

A pacifist, vegetarian and yoga practitioner, he dressed simply, avoided the limelight and remained wary of displays of power. He was a follower of the contemplative traditions of Taoism.

Mr. Moses wound up returning to Mississippi in the early 1990s to help launch the Delta Algebra Project as a direct continuation of his civil rights work.

“But this time, we’re organizing around literacy — not just reading and writing, but mathematical literacy,” he told the New York Times. “The question we asked then was: ‘What are the skills people have to master to open the doors to citizenship?’ Now math literacy holds the key.”