This issue of the AILA Review focuses on transdisciplinarity as the key to developing shared languages in and across domains and professional settings. The relationship and collaboration between researchers and practitioners have long been discussed within and across applied sciences and theoretical disciplines, mainly in the framework of transdisciplinarity (see AILA Review 31, 2018, for a recent overview). However, research approaches that claim to combine theoretical and practical needs and expectations often lack either solid grounding in empirical data or thorough reflection from theoretical perspectives. This special issue aims to take the discussion further by rethinking transdisciplinarity systematically from theoretical and practical angles. In so doing, we focus on developing shared languages that facilitate communication and mutual learning in multistakeholder discourses – with the ultimate goal of sustainably solving socially relevant problems. In the introduction, we present working definitions of our topic’s key terms (Part 1). We then go through the topics, results, and main interconnections of the six approaches examined in the papers included in this issue (Part 2). Based on the insights from the discussion so far, we set up a framework to systematically analyse three dimensions of developing shared languages: negotiation process, interplay of key drivers, and seizing opportunities (Part 3).