Because of Polish numerus clausus restrictions on Jews in university education [citation needed], he left Poland to study chemistry at the Sorbonne in France.

Tajfel's work with OSE involved resettling Jewish children, many of whom were orphans who had lost all their family.

Tajfel would often say that his work with OSE was the most important achievement in his life and he kept in touch with many of the children whose lives he helped to rebuild.

However, he was soon to meet his future wife Anna-Sophie Eber (Ann), who had been born in Germany but had moved to Britain before the Second World War.

He believed that the cognitive processes of categorization contributed strongly to the psychological dimensions of prejudice, which went against the prevailing views of the time.

Tajfel sought to discover whether the roots of prejudice might be found in "ordinary" processes of thinking, rather than in "extraordinary" personality types.

If the lines, which were presented individually, were shown without any category label, then errors of judgement tended to be random.

Imposing category distinctions on lines (A and B) was like dividing the social world into different groups of people (e.g., French, Germans, British).

Tajfel outlined these ideas in his article, "Cognitive Aspects of Prejudice", which was first published in 1969 and has been republished subsequently.

For this article, Tajfel was awarded the first annual Gordon Allport Intergroup Relations Prize by the Society for the Psychological Study of Social Issues.

[8] Having moved to Bristol University, Tajfel began his work on intergroup relations and conducted the renowned minimal groups experiments.

In these studies,[9][10] test subjects were divided arbitrarily into two groups, based on a trivial and almost completely irrelevant basis such as preference for the abstract paintings of Klee or Kandinsky.

[12] Even "on the basis of a coin toss...simple categorization into groups seems to be sufficient reason for people to dispense valued rewards in ways that favor in-group members over those who are 'different'".

Social identity theory suggests that people identify with groups in such a way as to maximize positive distinctiveness.

In 2019, evidence emerged documenting that Tajfel displayed inappropriate conduct toward female members of his lab.