Le Jeune was born to a Huguenot family in Vitry-le-François in the region of Champagne, France in 1591, and converted to Roman Catholicism at the age of sixteen.

[1] Le Jeune received a thorough preparation for the Jesuit priesthood; he was a novice for two years between 1613 and 1615, and he was deeply influenced by his mentor Father Massé, whom he met at the collège Henri IV de La Flèche.

During his studies, Le Jeune developed a keen interest in missions and became convinced that education was a key element in any successful attempt to spread Christianity.

While his work during those six months did not result in mass conversions as he had hoped, his ethnographic account of the Montagnais and his personal anecdotes about the cold, hunger, and conflicts he encountered are recorded in Relations des Jésuites de la Nouvelle-France of 1634.

Koemer suggests that Le Jeune's identification of a distinction between animate and inanimate nouns eventually assisted John Eliot in his grammar of the Natick language.

[4] Le Jeune decided that in order to effectively carry out his apostolate, he needed to establish mission settlements, on the model of Jesuit missionary work in San Ignacio Miní in Misiones Argentina and bordering region of Paraguay, a hospital to care for the aged and the ill, and schools for educating the young.

[2] He wrote: "I believe that souls are all made of the same stock, and that they do not materially differ; Hence, these barbarians having well formed bodies, and organs well regulated and well arranged, their minds ought to work with ease.

In a 1637 letter he cautions all missionaries not to make the "savages" wait for them when embarking in the morning, to never show distaste for any of their customs, and to help out during portages, or over-land journeys, from one river to another.

[11] Also on board were three Canonesses of St. Augustine of the Mercy of Jesus to establish a hospital underwritten by Marie Madeleine d'Aiguillon, niece of Cardinal Richelieu in response to a report from Le Jeune that had been published in the Relations in France.

The writings and experiences of Le Jeune and his fellow Jesuits are reflected in the Code Noir passed by France's King Louis XIV in 1685.

Le Jeune's influence was not limited to Canadian territories or seventeenth century Jesuits; when the French settled Louisiana, there was a clear sense that literacy and religion were interconnected.

In recognition of the work of the missionary life Paul Le Jeune, some geographic names have been assigned to this Jesuit who came from France, and founder of the hamlet of Trois-Rivières in 1634: