This article explores the implementation of dynamic assessment (DA) in an elementary school foreign language classroom by considering its theoretical basis and its applicability to second language (L2) teaching, learning, and development. In existing applications of L2 classroom DA, errors serve as a window into learners' instructional needs and provide opportunities for the teacher to mediate, prompting learners to reformulate their utterance. The investigation presented here draws on data from a combination of classroom DA and small-group work in a unit focused on Spanish interrogatives. Extending earlier studies (Davin, 2013; Davin & Donato, 2013), it critically evaluates the extent to which the teacher's DA records, the heart of DA assessment, provide sufficiently robust evidence for central claims in DA for the dynamic link between assessment and teaching in order to advance learner development. It does so by contextualizing the teacher's record with transcripts from small-group work that alternated with DA, and with a microgenetic analysis of two learners across both DA and small-group work. It concludes that whole classroom applications of DA will require considerable expertise on the part of teachers that would have to become part of teacher education programs. Equally importantly, it will benefit from being anchored in an explicitly meaning-oriented theory of language.