The article examines the mutual relations between the mendicants and guilds in the towns of Teutonic Order and Royal Prussia in the 14th–16th centuries. The preserved sources, in their widest extent, concern the issue of monastic prayer commitments. They show that, in relation to costs, only the largest and richest guilds could afford to have their own chapels, more had altars within monastic churches, and the poorest could only perhaps afford to pay individual monasteries for prayer obligations. The documents also indicate that at the time of the monastic economic crisis, caused by the progress of the Reformation and, consequently, the loss of income from the collection of alms and indulgences, they sought compensation for establishing cooperation with non–guild craftsmen, who, in exchange for paying fees to monasteries, were able to manufacture their products within their service buildings. These rights in Gdańsk and Toruń were confirmed by the king, usually specifying that the named individual could work only for the needs of the monasteries. Subsequent practice indicated that these provisions were violated, and attempts to sell goods caused numerous conflicts in which the town council became involved.