Indentured, or bonded, servants were an important source of labor in seventeenth- and eighteenth-century America. The term generally refers to immigrants who, in return for passage from Europe to America, had bound themselves to work in America for a number of years, after which time they would become completely free. The practice was closely related to the tradition of apprenticeship, in which a youth was assigned to work for a master in a certain trade and in return was taught the skills of the trade.
Convicts were another important source of colonial labor; thousands of English criminals were sentenced to labor in the colonies for a specified period, after which time they were freed.
Cottlieb Mittelberger came to Pennsylvania from Germany in 1750. He returned to Europe four years later. Mittelberger's own fortunes were not so bleak as those of his shipmates. Mittelberger served as a schoolmaster and organist in Philadelphia for three years. He returned to Germany in 1754.