The École normale supérieure - PSL (French pronunciation: ​[ekɔl nɔʁmal sypeʁjœʁ]; also known as ENS, Normale sup', Ulm or ENS Paris) is a grande école university in Paris, France. It is one of the constituent members of Paris Sciences et Lettres University (PSL).

Originally conceived during the French Revolution, the school was founded in 1794 to provide homogeneous training of high-school teachers in France but it later closed. The school was subsequently reestablished by Napoleon I as pensionnat normal from 1808 to 1822, before being recreated in 1826 and taking the name of École normale in 1830. When institutes for primary teachers training called écoles normales were created in 1845, the word supérieure (meaning upper) was added to form the current name. It has since developed into an institution which has become a platform for French students to pursue careers in government and academia.

The ENS has a highly competitive selection process consisting of written and oral examinations. The selection rates for International Selection vary from year to year, between 5 and 10% During their studies, many ENS students hold the status of paid civil servants.

The ENS is a grande école and, as such, is not part of the mainstream university system. However, the vast majority of the academic staff hosted at ENS belong to external institutions such as one of the Parisian universities, the CNRS and the EHESS. This mechanism for constant scientific turnover allows ENS to benefit from a continuous stream of researchers in all fields. ENS full professorships are rare and competitive. Generalistic in its recruitment and organisation, the ENS is the only grande école in France to have departments of research in all the natural, social, and human sciences.

Due to the selectivity of its entrance exam and its turnover among French researchers, it has a high proportion of prize laureates and therefore a very good reputation. Its alumni include 14 Nobel Prize laureates (ENS has the highest proportion of Nobel laureates among its alumni of any institution worldwide), of which 8 are in Physics, 12 Fields Medalists, more than half the recipients of the CNRS's Gold Medal (France's highest scientific prize) and several hundred members of the Institut de France, and scores of politicians and statesmen. The school has achieved particular recognition in the fields of mathematics and physics as one of France's foremost scientific training grounds, along with international notability in the human sciences as the spiritual birthplace of authors such as Julien Gracq, Jean Giraudoux, Assia Djebar, and Charles Péguy, philosophers such as Henri Bergson, Jean-Paul Sartre, Louis Althusser, Simone Weil, Maurice Merleau-Ponty and Alain Badiou, social scientists such as Émile Durkheim, Raymond Aron, and Pierre Bourdieu, and "French theorists" such as Michel Foucault and Jacques Derrida. The school's students are often referred to as normaliens.

Its model has been replicated elsewhere, in France (at the ENSes of Lyon, Paris-Saclay, and Rennes), in Italy (at the Scuola Normale Superiore in Pisa), in Romania, in China and in former French colonies such as Morocco, Algeria, Mali, Mauritania, and Cameroon.