This book aims to offer a new perspective and a new methodology which provide a tool for all researchers in historical sociology of language, but also social history, cultural history, historical sociolinguistics and the fields of research that link language and society, in a diachronic perspective but also in a synchronic perspective. The original point of view from which this methodology arises is Basque studies, but it can almost completely be applied to any international linguistic context, with some little changes. This work is the result of a long methodological reflection that has been developed in different publications. This book is a presentation of the taxonomy and the methodology proposal that our team has created to help sociology of language and sociolinguistics researchers in their work. The taxonomy was created to analyse and classify the sociolinguistic information taking into account the most usual variables that arise in the international bibliography linked to the sociology of language. To create that methodology, we have examined methodological findings since the foundation of sociolinguistics and the tools it has developed, as well as its main theoretical concepts and, bearing our task in mind, we have tried to put together a wide-ranging, flexible and detailed methodology.