Conversation-for-learning (Kasper and Kim 2015) is a pedagogical arrangement set up with a view to maximizing the potential benefit of interaction for language learning. As participants for conversation-for-learning are recruited for their relative expertise in the target languages, the talk is often characterized by asymmetries in knowledge and language expertise. Based on sequential analysis of how the knowledge asymmetries are brought to the fore of interaction and how they are subsequently dealt with, the current study illustrates how learning opportunities are generated in conversation-for-learning, that is, by collaborative achievement of definition sequences (Markee 1994). Interaction provides an observable space where interactional practices deployed by the participants to achieve and maintain intersubjectivity can be observed and appropriated. The study contributes to our understanding of language learning as a social practice as it shows that the methods and devices that underlie and enable human sociality constitute the cornerstones of what makes language learning happen in interaction.