But children of blue-collar workers, who made up as much as 20 percent of the student body of the top grandes écoles 30 years ago, make up, at best, 2 percent today. Few are minority students.

In the 1950's, only a small proportion of French students pursued higher education, leaving room for a slice of the working classes to get into the schools, said Vincent Tiberj, a sociologist who studies social inequalities in France. Since then, the number of candidates for the schools has expanded far faster than the schools themselves.

At the same time, the channels leading into the schools have narrowed: the vast majority of students entering the grandes écoles today come from special two-year preparatory schools, which draw their students primarily from high schools in the country's wealthiest neighborhoods. "The top five or six grandes écoles recruit students from fewer than 50 high schools across France," said Richard Descoings, director of the elite Paris Institute of Political Studies, better known as Sciences Po.

Administrators at the grandes écoles say students who do not follow the focused, specialized curriculum of the preparatory schools have almost no chance of being accepted. And while, theoretically, top students from any high school in the country can apply for the preparatory schools, the system has become so rarefied that few people from working-class neighborhoods are even aware that the opportunity exists.

"There's a lack of information, no one talked to us about the preparatory schools," said Alexis Blasselle, 20, the daughter of working-class parents and now a student at the exclusive École Polytechnique. She learned of the preparatory schools by chance the summer after graduating from high school. "The solution isn't to open up another avenue to get into the grandes écoles, but to make people aware of the possibility."

Sciences Po (pronounced see-ahns po), alone among the elite schools, has opened a new avenue of entry for students. High schools from disadvantaged neighborhoods nominate students, and Sciences Po then gives them oral examinations for intellectual curiosity and critical thinking. This year, 50 students were admitted through the program, while 200 entered through the normal examination process.

The Conference of Grandes Écoles, an association of the 200 schools, has also started a program that reaches out to top students in working-class neighborhoods to help guide them through their high school years and better their chances of getting into a preparatory school.