The Movement of Priests for the Third World (Spanish: Movimiento de Sacerdotes para el Tercer Mundo, MSTM) was a tendency among the Catholic Church in Argentina which aimed at combining reform ideas which followed the Second Vatican Council with a strong political and social participation.
The CELAM declaration of Medellín (August 1968) tied poverty in the Third World to exploitation by multinational firms of industrialized countries, supporting liberation theology.
Three priests from Buenos Aires, Héctor Botán, Miguel Ramondetti and Rodolfo Ricciardelli had published, a month earlier, the Manifiesto de los 18 Obispos (Manifest of the 18 Bishops), which proposed, among other suggestions, the creation of the MSTM.
The first encounter took place in May 1968, with the tacit authorization of the bishops Guillermo Bolatti, Enrique Angelelli, Alberto Devoto, Jerónimo Podestá, Jaime de Nevares [es], Adolfo Tortolo and Vicente Faustino Zazpe, although none of them would associate themselves with the Movement of Priests for the Third World.
In December 1969, more than 20 priests, members of the MSTM, marched on the Casa Rosada to present to Onganía a petition pleading him to abandon the eradication plan of villas miserias.