Worker-priest was a missionary initiative by the French Catholic Church in particular for priests to take up work in such places as car factories to experience the everyday life of the working class. A worker-priest was any priest who was "freed from parochial work by his bishop, lived only by full-time labor in a factory or other place of work, and was indistinguishable in appearance from an ordinary workingman".
Although the movement did spread to many other countries such as Belgium and Italy, the French were always the most prominent.
The movement was an attempt to "rediscover the masses" of industrial class workers who had become largely disaffected with the church.
Father Jacques Loew, who began working in the docks of Marseilles in 1941, effectively started the worker-priest movement. Loew had been sent by his Dominican Father Lebret to "study the condition of the working classes" but not to actually join the workers.
In 1944, the first worker-priest missions were set up in Paris, and then later in Lyons and Marseille. The Church hoped, by "putting young priests into secular clothes and letting them work in factories, to regain the confidence of the French working class, which [had] almost completely abandoned the Catholic faith."
In 1945, Pope Pius XII "approved (reluctantly) the daring social experiment of the French worker-priests." However, in the early 1950s, the worker-priest movement fell out of favor with the Vatican due to their role in left-wing politics and perceived abandonment of the traditional priesthood. The Worker-Priest movement was "severely constrained by a series of measures taken by the church in the 1950s".
In 1950, Pius XII in an apostolic exhortation on the priestly life expressed "reservations and suspicions of the worker-priests …" Loew's May 1951 report defending the movement, written to Giovanni Montini (future Pope Paul VI), the assistant Cardinal Secretary of State, was not well received.
Many of the priests joined in campaigns for improved pay and conditions and the movement became prominent in the industrial unrest of 1952 and 1953. This resulted in the factory owners complaining to the Catholic Church that the priests were being divisive by supporting the unions.