Moscovici was born in Br?ila into a Jewish family, the son of a grain merchant. He frequently relocated, together with his father, spending time in Cahul, Gala?i, and Bucharest. Later, he indicated that his stay in Bessarabia had contributed to his image of a homeland. From an early age, Moscovici suffered the effects of anti-semitic discrimination: in 1938, he was expelled from a Bucharest high school on the basis of newly-issued anti-semitic legislation. In later years, he commented on the impact of the Iron Guard, and expressed criticism for intellectuals associated with it (Emil Cioran and Mircea Eliade).

Moscovici trained as a mechanic at the Bucharest vocational school Ciocanul. Faced with an ideological choice between Zionism and communism, he opted for the latter, and, in 1939, joined the then-illegal Romanian Communist Party, being introduced by a clandestine activist whom he knew by the pseudonym Kappa.

During World War II, Moscovici witnessed the Iron Guard-instigated Bucharest Pogrom in January 1941, and was later interned by the Ion Antonescu regime in a forced labor camp, where, together with other persons of his age, he worked on construction teams until being set free by the Soviet Red Army in 1944. During those years, he taught himself French and educated himself by reading philosophical works (including those of Baruch Spinoza and René Descartes).

Subsequently, Moscovici travelled extensively, notably visiting Palestine, Germany and Austria. During the late stage of World War II he met Isidore Isou, the founder of lettrism, with whom he founded the artistic and literary review Da towards the end of 1944 (Da was quickly censored). Refusing promotion on the basis of political affiliation at a time when the Communist Party participated in Romania's governments, he became instead a welder in the large Bucharest factory owned by Nicolae Malaxa.

Initially welcoming Soviet occupation, Moscovici grew progressively disillusioned with communist politics, and noted the incidence of antisemitism among Red Army soldiers. As the communist regime was taking over and the Cold War erupted, he helped Zionist dissidents cross the border illegally. For this, he was implicated in a 1947 trial held in Timi?oara, and decided to leave Romania for good. Choosing clandestine immigration, he arrived in France a year later, passing through Hungary and Austria, and spending time in a refugee camp in Italy.

In Paris, helped by a refugee fund, he studied psychology at the Sorbonne, while being employed by an industrial enterprise. At the time, Moscovici became close to Paris-based writers, including the Romanian-born Jewish Paul Celan and Isaac Chiva. In reference to himself, Celan, and Moscovici, Chiva later recalled: "For us, people on the Left, but who had fled communism, the first period in Paris, in a capital where the intellectual environments were developing under full-scale Stalinist enthusiasm, was very harsh. We were caught between a rock and a hard place: on one side, the French university environment who saw us as «fascists». [...] On the other, the Romanian exiles, most of all the nationalist students, when not outright on the far right, who did not shy away from denouncing us as communist «moles» in the pay of Bucharest or Moscow."

Moscovici's 1961 thesis (La psychanalyse, son image, son public), directed by the psychoanalyst Daniel Lagache, explored the social representations of psychoanalysis in France. Moscovici also studied epistemology and history of sciences with philosopher Alexandre Koyré. During the 1960s, he was invited to the United States by the Princeton University's Institute for Advanced Study; he also worked at Stanford University and Yale, before returning to Paris to teach at the École pratique des hautes études. Serge Moscovici has been a visiting professor at the The New School in New York City, at the Rousseau Institute in Geneva, as well as at the Université catholique de Louvain and the University of Cambridge.

By 1968, together with Brice Lalonde and others, he became involved in green politics, and even ran in elections for the office of Mayor of Paris for what later became Les Verts. A doctor honoris causa of several universities, Moscovici was the recipient of the Balzan Prize in 2003 for Social Psychology.

In 1997, Serge Moscovici authored an autobiographical essay titled Chronique des années égarées ("Chronicle of the Mislaid Years"). It was translated into Romanian as Cronica anilor risipi?i (published by Polirom in 1999).

His research focus was on group psychology and he began his career by investigating the way knowledge is reformulated as groups take hold of it, distorting it from its original form. His theory of social representations is now widespread in understanding this process of cultural Chinese whispers. Influenced by Gabriel Tarde, he later criticized American research into majority influence (conformity) and instead investigated the effects of minority influence, where the opinions of a small group influence those of a larger one. He also researched the dynamics of group decisions and consensus-forming.

Minority influence

Moscovici claimed that majority influence in many ways was misleading — if the majority was indeed all-powerful, we would all end up thinking the same. Drawing attention to the works of Gabriel Tarde, he pointed to the fact that most major social movements have been started by individuals and small groups (e.g. Christianity, Buddhism, the Suffragette movement, Nazism, etc) and that without an outspoken minority, we would have no innovation or social change.

The study he is most famous for, Influences of a consistent minority on the responses of a majority in a colour perception task, is now seen as one of the defining investigations into the effects of minority influence:

• Aims: To investigate the process of innovation by looking at how a consistent minority affect the opinions of a larger group, possibly creating doubt and leading them to question and alter their views
• Procedures: Participants were first given an eye test to check that they were not colour blind. They were then placed in a group of four participants and two confederates. they were all shown 36 slides that were different shades of blue and asked to state the colour out loud. There were two groups in the experiment. In the first group the confederates were consistent and answered green for every slide. In the second group the confederates were inconsistent and answered green 24 times and blue 12 times.
• Findings: For 8.42% of the trials, participants agreed with the minority and said that the slides were green. Overall, 32% of the participants agreed at least once.
• Conclusions: The study suggested that minorities can indeed exert an effect over the opinion of a majority. Not to the same degree as majority influence, but the fact that almost a third of people agreed at least once is significant. However, this also leaves two thirds who never agreed. In a follow up experiment, Moscovici demonstrated that consistency was the key factor in minority influence, by instructing the stooges to be inconsistent. The effect fell off sharply.