Missionary activities were very strong in Poland before the Second World War. The establishment of a Communist regime after 1945 led to a break in the number of missionaries sent worldwide and, soon after, to a liquidation of all missionary institutions in the country. Because the Catholic Church was very strong, the state did not dare to launch an immediate and frontal attack on the church until 1947. From 1948 however, a full-blown campaign against the church began with nationalization, imprisonments and prohibitions, notably of mission activities. After 15 years, however, some forms of compromise between church and state began to appear. This allowed the Church to rebuild its missionary movement – as of 1965. The year 1980 saw the emergence of the Solidarity movement and the begining of the unmaking of Communism. It led to a revitalization of missionary activities and a normalization of church and state relations, particularly after 1989. The present article describes these developments, establishes a chronology and tries a first causal explanation of the decline and subsequent return of missions in Poland. It also looks at the inheritance of the Communist period for the Catholic Church in Poland.