This paper deals with origins and scope, problems and principles, and three directions within historical sociolinguistics: a) a historical sociology of language; b) the historical variationist approach; and c) the ethnographic-interactional dimension: towards a third wave historical sociolinguistics. Historical sociolinguistics developed as a new approach to diachronic linguistic research in the last third of the twentieth century, at the intersection of historical linguistics and sociolinguistics with other interrelated fields like social history and corpus linguistics, among others. It derived from the basic “underlying premise that linguistic and social factors are clearly interrelated in language change” and the need to study them “in their mutual interaction” (Roberge 2006: 2308). The maturity currently achieved by historical sociolinguistics has been profitable to the two main branches at whose intersection it originally developed: sociolinguistics and historical linguistics. By being applied to the interpretation of texts from the past, the former has now tested the ‘universal’ validity of its methods and tenets, which – originally devised for present-day situations – are now “put to the test of time” (Nevalainen and Raumolin-Brunberg 2003: 202). At the same time, the interdisciplinary dialogue between present and past has allowed historical linguists to gain new insights into historically attested changes which can now be seen within a more dynamic, interpersonal dimension, and in the light of some of the external circumstances that surrounded and could have explained them. This review only purports to attest to the vitality of the discipline and to show how a historical sociolinguistic methodology – adapted to the requirements of each different dimension – is now well-established and has proved useful for the interpretation of historical variation and change and in the history of various languages. The future agenda will no doubt need to explore deeply some of the interconnections between these subfields. The principle of ‘informational maximalism’ can, in this sense, be as proactively inspiring as the ‘uniformitarian’ tenet was for the inception of the discipline, allowing for the reconstruction of variation and change at various levels of abstraction and accommodating the findings of historical ethnographers, sociologists and sociolinguists within a richer inter- and cross-disciplinary field.