Were ordinary factory workers unskilled and was technology "de-skilling" during the Industrial Revolution? I measure foregone output to estimate the human capital investments in mule spinners and power loom tenders in ante-bellum Lowell. These investments rivaled those of craft apprentices. Although factory workers were unskilled in a sense, the implementation of this technology depended on the development of a labor force with substantial human capital. From 1834-55, firms made increasing investments in skill, allowing workers to tend more machines, thus raising labor productivity. This growing investment was motivated partly by changing factor prices and more by a changing labor supply. Calculations show that firm policy and social conditions, including literacy, influenced the investment in factory skills. When skills are considered, technological change at Lowell appears as a broad social process, dependent as much on innovation in institutions as on invention of machines.