This collection explores the relationships between theory and evidences in functional linguistics, bringing together perspectives from both established and emerging scholars. The volume begins by establishing theoretical common ground for functional approaches to language, critically discussing empirical inquiry in functional linguistics and the challenges and opportunities of using new technologies in linguistic investigations. Building on this foundation, the second part of the volume explores the challenges involved in using different data sources as evidence for theorizing language and linguistic processes, drawing on work on lexical cohesion in language variation, neuroimaging and neuropathological data, and keystroke logging and eye-tracking. The final section of the volume examines the ways in which evidences from a wide range of data sources can offer new perspectives toward challenging established theoretical claims, employing empirical evidences from corpus linguistic analysis, keystroke logging, and multimodal communication. This pioneering collection synthesizes perspectives and addresses fundamental questions in the investigation of the relationships between theory and evidences in functional linguistics and will be of particular interest to researchers working in the field, as well as linguists working in experimental and interdisciplinary approaches which seek to bridge this gap.