We report on a case study on pedagogical affordances of intercultural telecollaboration for authentic communication practice and competence development in the local foreign language. Focus is on spoken and written conversations involving pairs of secondary school pupils of different linguacultural backgrounds. Particular attention is given to three task design features: multimodal home access to telecollaboration, lingua franca use of the target language, and soft intercultural topics addressing pupils' everyday concerns and experiences. Performance analyses of recorded conversations and reflective interviews reveal significant pedagogical advantages of the chosen task design features. The online lingua franca conversations are marked by a high degree of cooperative autonomy with an emphasis on creating common ground, negotiating a shared line of argumentation, ensuring a supportive and consensual atmosphere, and solving communication problems on the fly. [For the complete volume, see ED571330.]