Telecollaborative research often focuses on intercultural objectives rather than language learning, and highlights limitations due to technical difficulties and poor task design. This study redresses the balance by focusing on language and learner interaction in an exchange involving the English as a Foreign Language (EFL) learners of 35 secondary school student-teachers in two European countries. The teachers were enrolled in courses on technology for language education, and collaborated in a virtual environment to devise interactive tasks for their learners. Analyses of student-teacher course contributions, the teaching/learning materials they designed, and their reflections on this work shed light on the affordances of telecollaboration from a task-based language teaching perspective. [For the complete volume, see ED571330.]