This chapter describes two basic aspects of the process of proletarianisation in the nitrate enterprises: the origins of the labour force and its living and working conditions. British, Peruvian and Chilean enterprises were the major producers responsible for an impressive upsurge in nitrate exports. The complex social phenomenon of Popular Unity during the early 1970s, in which organised workers played a significant role, cannot be explained without referring to the strong historical roots of the working class movement in Chile. An intermittent flow of emigrants from that region can be traced back to the 1830s, mainly connected with mining-related ventures, whether silver or guano in Peru or gold in California. This early flow of emigrants has to be construed as crucially important in the formation of the proletariat in the nitrate region, because it entailed the full transformation of a rural-based labour force into a modern working class.