This paper presents and discusses quantitative recall data from a longitudinal study that investigated the effects of Dynamic Assessment (DA) on diagnosing and promoting listening comprehension in French as a second language. We first define the theoretical concept of DA based on Vygotsky's Zone of Proximal Development, which integrates mediation and assessment into a unified pedagogical activity; next we outline the research design of the study, rooted in Vygotskyan genetic methodology; finally, we provide a microgenetic analysis of learner recall of idea units contained in three different authentic aural text genres. The data show improvement in listening ability as measured by an increase in the number of idea units recalled over time and as a result of mediation. It also shows that learners are able to transfer their ability, to some extent, to more complex texts. We explain the constraints on transferability. (Contains 7 notes and 4 tables.)