The concept of the zone of the proximal development can contribute not only to the assessment, but also to the teaching within the second language learning environment. However, the unifying philosophy within sociocultural theory (SCT) in relation to language and thought has also merged the assessment and teaching procedures into the concept of Dynamic Assessment (DA). The process of DA lets the teacher/mediator permeate into both the actual and potential zones of the development. It teaches and assesses at the same time. This contributive and critical article focuses on the peculiarities of DA. It introduces two new approaches within DA: Dynamic Assessment and Teaching (DAT), and Dynamic Teaching and Assessment (DTA). Moreover, it will discuss where DA stands within applied linguistics, the idea of transcendence both as the device of development and assessment, and the doubts applied linguists might have regarding the promising outcome of metacognitive awareness as a key point in the process of development in DA. After evaluating the problem of validity and reliability of DA, the article will critically analyze the two realizations of DA: interactionist and interventionist. Finally, the mere process of development within SCT in general, and DA in particular will be discussed.