For Vygotsky, language is a cultural-psychological concept emerged from social interactions and is applied for higher cognitive functions such as thinking, meaning making, and knowledge construction. In this study, a sociocultural perspective was applied to analyze the language produced by 40 sophomore Iranian EFL learners during dialogic interactions on writing tasks in order to investigate: 1) the talk types that students produced, and 2) the agency they employed to make meaning through languaging. The typology of talk proposed by Mercer (2004) was used as a framework for talk analysis. Seven categories of talk were found in the corpus, among which, Cumulative talk had the highest frequency. The students exercised two types of agency during interactions, debilitative agency in Disputational talks and facilitative agency in Cumulative and Exploratory talks. The categories of talk, their frequencies, and the amount of agency the students employed in the categories of the talk can be justified by Lantolf and Poehner's (2014) argument that the interactions and dialogues considered micro-level practices are affected by macro-level structures in which they are developed.