Although co-authoring is commonly practised, we know little about its actual process. How do authors choose their collaborators? How do they make decisions about the writing process? What obstacles do they face and how do they overcome them? What do they see as the benefits and pitfalls of coauthoring? This article begins by demonstrating the prevalence of co-authoring of journal articles in the field of Applied Linguistics and TESOL. The somewhat limited literature on authoring, particularly collaboration, is reviewed. Using a duoethnographic approach, as researcher-participants we research our own co-authoring process and present our findings in a case study. Key ideas related to choosing and working effectively with co-authors and important qualities in a co-author are discussed, encapsulated in the maxims of mutual benefit and relationship building. We also reflect on our experience of using duoethnography to capture disruptions to our thinking about the co-authoring process and developments in our understanding of ourselves as writers and of our relationship as coauthors. The article concludes by reiterating the benefits that both less experienced and more experienced authors can derive from co-authoring and by recommending co-authoring as an important supportive and collaborative practice for professional development.