This study examined how Turkish-speaking preschoolers displayed oppositions in their peer interactions through two adversative discourse markers, "ya" and "ki". These two markers differ in their syntactic mobility. The data came from seminaturalistic peer interactions of 78 preschoolers. The discursive properties of children's utterances with "ya" and "ki" were quantitatively and qualitatively analyzed. The analyses suggested that due to the differences in their syntactic mobility, these two discourse markers flagged alternative types of oppositions. "Ki", the less mobile marker, was more tightly linked to the propositional content and challenged the relevance of the prior utterance, rather than directly disagreeing with it. Such uses minimized opposition. On the other hand, "ya", the more mobile marker, was semantically more independent of the proposition to which it was attached and marked opposition at a more global level. "Ya"-utterances were mostly in the form of counters, such as "Ya stop!" -- "Ya stop!", which escalated conflicts.