In 1575 Fyodorov, now in the service of Prince Konstanty Wasyl Ostrogski, was placed in charge of the Derman Monastery near Dubno; in 1577–9 he established the Ostrog Press, where, in 1581, he published the Ostrog Bible in Church Slavonic - the first full version of the Bible printed in moveable type, as well as a number of other books.