The Pavia Diachronic Emergence of Alignment (DEmA) database is a new resource for the study of the diachrony of alignment patterns cross-linguistically. In this paper, we offer a description of DEmA, its structure and the choices that have been made in its construction. The main goal of DEmA is to offer a platform that makes it possible to investigate the sources and processes out of which new alignment patterns come into being across languages. In order to do so, each instance of the emergence of a construction with a new alignment pattern is decomposed into a number of well-defined parameters pertaining to the initial situation in the language, the developmental mechanisms leading to the new alignment .pattern, and the effects of the change. These various parameters are effectively implemented into a searchable format. This systematization enables users to easily retrieve and compare various type of information concerning the emergence of alignment patterns in the world’s languages.