This article analyzes the uses and semantic variations of the concepts of socialism and communism during the nineteenth century in Chile. Based on a systematic review of the controversies in the Chilean public sphere over these terms, is examined the conceptual shift from predominantly negative notions in the 1840s to a positive assessment of them by the end of the century. As a result of a variety of social and political transformations, both locally and transnationally, the concepts of socialism and communism were cdefined as an exacerbation of the democratic ideology which led to radical projects of social equalization and disruption of the property regime, or as irreligious doctrines that undermined the established social order. Only at the end of the nineteenth century it is possible to observe an effort of conceptual resignification when the first movements that openly adopt socialism as an ideology appear and identify partisanly with it.