After recovering from his wounds in 1945, Beynar decided to leave the resistance, and instead began publishing in an independent Catholic weekly "Tygodnik Powszechny". It was then that he took the pen-name Jasienica (from the name of the place where he had received treatment for his injuries) in order not to endanger his wife, who was still living in Soviet-controlled Vilnius, Lithuania. Soon he became a member of the weekly's staff and then an editor. In 1948 he was arrested by the Polish secret police () but after several weeks was released after the intervention of Bolesław Piasecki from the PAX Association. In gratitude to Piasecki, therefater he worked with PAX, leaving "Tygodnik Powszechny" for PAX in 1950. In 1950, he became a director of the Polish Caritas charity. Jasienica became a member of the Crooked Circle Club, which espoused free speech and open discussion. His essays were published in "Dziś i Jutro", "Słowo Powszechne", "Życie Warszawy", "Po Prostu". From at least this period until his death he would live in Warsaw. His wife Władysława died 29 March 1965.