 In 1947 he created the PAX Association and was the chairman of its governing body (until his death).After 1956, the importance of PAX diminished (and Piasecki's role along with it), though it remained a prominent organisation until 1989 and its successors still exist today.In later years, Piasecki was a member of the Polish Sejm from 1965, where he presided over the grouping of members associated with PAX.