à lasco) (1499-1560. Nephew of Jan Laski, archbishop of Gniezno and primate of Poland, the younger Jan benefited from his uncle's aid especially in ecclesiastical preferments and his treatment by distinguished people abroad. In 1521 he was ordained priest and appointed dean of Gniezno. With his elder brother Jerome he went on many diplomatic missions for his uncle and for Poland and thereby met (and even bought the library of) Erasmus in Basle. Soon after this he had made contacts with both Zwingli and Oecolampadius. Exactly when his conversion to Protestantism occurred is not known, but it was probably completed by 1538 when, being offered a Polish bishopric, he abruptly departed for Frankfurt-am-Main. Thence he moved to Louvain, where he married. Next he was in Emden in Frisia where in 1543 he became superintendent of the churches in the territory of Countess Anna of Oldenburg.
A gifted organizer, Laski used the type of discipline favored by Oecolampadius. As the major link in this order he established the Coetus, which was composed of all the clergy and which met each Monday in Emden from Easter to Michaelmas. The Interim of 1548 necessitated his departure, and in 1550 he arrived in England. He was granted the use of the church of the Austin Friars for the German, Dutch, Belgian, and French Protestants and as superintendent of the “churches of strangers” was given a free hand in preaching, teaching, worship, and discipline-a unique concession. He published an influential book on church discipline and also a confession of faith and a catechism. His only real friend among the bishops was. Following the death of his protector, Edward VI, he had to leave England. He ended his days as superintendent of the Reformed churches of S Poland.
See O. Bartel, Jan Laski (1955), and B. Hall, John à Lasco (1971).