This thesis investigates the female labor force of the Lowell textile mills from 1820 to 1850. First, it describes the development of the Lowell system and the philosophy on which it was founded. Next, it examines the working conditions in the mills and the daily lives of the women who worked in them. Finally, it describes the circumstances that brought about labor unrest and ultimately a complete change in the work force at Lowell, from the young, single, New England farm women to immigrant laborers. A variety of primary sources, such as letters, diaries, essays and poems written by the mill workers themselves, provide insights into how these women viewed their work, their lives, and the events that transformed the factories and city of Lowell. / Master of Arts