Lee Harvey Oswald’s exact motive for killing President John F. Kennedy has never been definitively established, and historians agree that any answer is ultimately an informed reconstruction rather than a proven fact.

Below is how most serious research and discussion breaks the question down.

1. What the official investigations said

  • The Warren Commission concluded that Oswald killed Kennedy and acted alone, but it could not identify a single clear motive that met “reasonable” standards.
  • It reviewed possible drivers such as Marxist/communist beliefs, personal grievance, desire to change society, or a wish for notoriety, and found that none fully explained his act by themselves.
  • Later historical work often starts from the same point: who did it seems clearer than why he did it.

2. Ideology and politics

Oswald was an avowed Marxist who had a long record of radical political identification. Key points often cited:

  • He developed an interest in Marxism as a teenager, talked about class exploitation, and even mentioned killing a president in political conversations in the 1950s, according to a friend who later testified.
  • He defected to the Soviet Union, then became disillusioned there and returned to the United States, which suggests a pattern of extreme ideological swings and frustration.
  • He supported Fidel Castro and the Cuban revolution, created a small “Fair Play for Cuba” front in New Orleans, and was angered by U.S. policy toward Cuba after events like the Bay of Pigs.

Many historians therefore argue that Oswald saw Kennedy as a symbol of U.S. capitalism and anti‑communist policy, and that attacking him fit Oswald’s radical, pro‑Cuba, Marxist self‑image.

3. Personal failure, resentment, and the need to feel important

A strong line in modern scholarship emphasizes Oswald’s personality and life history more than pure ideology. Common themes:

  • He grew up with instability and little structure, was often described as a misfit, and had difficulty holding jobs or maintaining relationships, including his marriage.
  • Authors describe him as someone who repeatedly failed “as a man, a husband, a worker, a Marine and a son,” which fed a deep sense of inadequacy.
  • Some psychological analyses argue he fit the profile of a certain kind of murderer for whom violence becomes a way to resolve inner feelings of humiliation and insignificance.

Under this view, killing Kennedy was partly a bid for recognition and significance : a way to “go down in history” and transform a life he experienced as failure into something dramatic and meaningful.

4. Pattern of seeking dramatic acts

Oswald’s path in the years before November 1963 shows a pattern of escalating, attention‑seeking political gestures. Examples frequently noted:

  • Defecting to the Soviet Union expecting it would make him important, only to be treated as a nuisance.
  • Returning to the United States and finding that almost no one cared, which frustrated his hopes of being taken seriously.
  • Creating the “Fair Play for Cuba” group, handing out leaflets, and staging small confrontations, apparently aiming for public attention and a route to Cuba, but again getting little response.
  • Attempting to shoot General Edwin Walker, a right‑wing segregationist in Dallas, months before the Kennedy assassination; this shows he was already willing to kill a political figure to express his beliefs and anger.

When Kennedy’s motorcade route passed directly in front of the building where Oswald worked, some historians think he saw a sudden, practical chance to commit the dramatic political act he had been building toward.

5. Conspiracy theories vs. lone‑gunman explanations

Public debate has long gone beyond Oswald’s internal motives to ask whether he acted alone at all.

  • For decades, people have proposed conspiracies involving the Mafia, the CIA, anti‑Castro exiles, the Soviets, or others, often arguing that Oswald was a patsy or part of a larger plot.
  • Official investigations (including the Warren Commission and later reviews) identified Oswald as the assassin and found no conclusive proof that a larger conspiracy controlled him, though some later inquiries left the door open to the possibility of additional gunfire or organized‑crime involvement.
  • Even authors who take Oswald as the gunman disagree over whether his motives were personal and psychological, primarily ideological, or partly shaped by any contacts with intelligence or extremist networks.

For your specific phrase “why did Lee Oswald kill JFK,” the mainstream historical answer is that he acted on a volatile mix of radical left‑wing ideology, anger at U.S. policy (especially toward Cuba), long‑standing feelings of failure and resentment, and a powerful need to make himself important through a spectacular act of political violence.

Bottom line:
We do not have Oswald’s own clear, reliable explanation, and experts caution that no single motive fully explains his decision. The best evidence suggests a combination of political extremism, personal frustration, and a desire for notoriety, rather than one simple reason.

Information gathered from public forums or data available on the internet and portrayed here.