This chapter studies the development of a work force in Oruro which was the second most important Upper Peruvian mining center throughout the colonial period. Although a major comparative study of labor in the silver mines of colonial Mexico and Upper Peru (present-day Bolivia) has yet to be published, a number of monographs have appeared about mining in each of these important mineral producing areas. But the settlement of Oruro is not the only example of people putting up with considerable hardship during a mining boom. Despite its undeniable climatic disadvantages, Oruro was in a favorable geographical position in a number of ways. Despite the fact that the mine workers’ practice of carrying away mineral was viewed by the owners as a necessary evil, there were constant attempts to police the situation and to keep theft within acceptable limits.