For years, the study of spoken languages, on the basis of written and then also oral productions, was the only way to investigate the human language capacity. As an introduction to this first volume of Languages in Contrast devoted to the comparison of spoken and signed languages, we propose to look at the reasons for the late emergence of the consideration of signed languages and multimodality in language studies. Next, the main stages of the history of sign language research are summarized. We highlight the benefits of studying cross-modal and multimodal data, as opposed to the isolated investigation of signed or spoken languages, and point out the remaining methodological obstacles to this approach. This contextualization prefaces the presentation of the outline of the volume.