In this study, we compared the impact of audio-, video-, and text-chat interaction on target language use during online learner-learner interaction and on learner affect amongst adolescent learners of German as a foreign language. Repeated measures and ANOVA analyses revealed a high percentage of target language output in all conditions for all four tasks, especially in text- chat. Audio-chatters produced the most output and used the most meaning negotiation, compensation strategies, self-repair and other-repair strategies. Learners in all conditions gained in enjoyment, willingness to communicate and self-efficacy. Anxiety reduced for text-chatters. Task effects partly determined the quantity of L2 output, while condition effects determined meaning-oriented and form-focused processing.