This study examined the effect of structural and content characteristics of language tasks on foreign language learners' conversational negotiations. In a 2x2 Greco-Latin square design, degree of structural support of language tasks, students' degree of familiarity with German video segments, and task order were varied. Twenty-eight pairs of third-semester German-language students were videotaped while interacting with each other in computer-supported language learning environments. Transcripts of their conversational exchanges were analysed with regard to indices of conversational negotiations, coded on a functional level and a topical level. Results showed a large effect of structural task support, with the Low Support Task being associated with negotiating exchanges in German to a greater degree than the High Support Task. In addition, students' conversations about single topics were significantly longer than in the High Support Task, which already provided linguistic content for discussion. The effect of content familiarity was evident primarily in its relation to task order, with the unfamiliar video aggravating order effects. In the discussion, the perception of communicative task affordances for conversational negotiations in a foreign language is emphasized.