A plethora of research has shown that academic self-concept (ASC) – as the mental representation of one’s academic ability – is crucial for promoting desirable learning and life outcomes. The need to rigorously examine the dynamics of ASC, that is, its pattern of growth, change, and development, is therefore evident. However, longitudinal ASC research has almost exclusively examined dispositional self-reports on ASC spanning rather long time slots in focusing on students’ habitual ASC (trait ASC), whereas comprehensive research on state fluctuations in ASC (state ASC) across time is virtually missing. Consequently, despite some evidence that ASC is object of considerable short-term variation, our knowledge dwindles rapidly when it comes to determining to what extent state ASC provides a meaningful extension of our current understanding of ASC.With DynASCEL, we will change that by probing the dynamics of students’ ASC in their everyday life at school. To this end, we will innovatively implement ambulatory assessment via smartphones to measure students’ state ASC several times per day (in every school lesson) for a period of three weeks. Thereby, we will center DynASCEL around general-school ASC, as well as domain-specific ASCs in the subjects of mathematics, physics, German, and English. In this, we aim to gather a full-fledged understanding of the (1) structure, (2) processes, (3) intraindividual variability, and (4) nomological network of ASC dynamics in everyday life. To achieve Objective 1 (the structure of ASC dynamics in everyday life), we will comprehensively investigate state fluctuation of ASC around students’ habitual (trait) ASC aiming at ultimately establishing the concept of state ASC in the scientific field. For Objective 2 (the processes of ASC dynamics in everyday life), we will thoroughly strive towards an in-depth understanding of the formation of ASC on a situation-to-situation basis by investigating the interplay between different state ASCs as well as between state ASC and achievement across and within domains. For Objective 3 (the intraindividual variability of ASC dynamics in everyday life), we will examine the genesis and stability of (as well as possible transitions between) ASC profiles from situation to situation. And finally, for Objective 4 (the nomological network of ASC dynamics in everyday life), we will investigate the role of everyday ASC dynamics in the broader realm of a nomological network encompassing a number of concurrent learning-related constructs, characteristics, and outcomes.To tackle these four objectives, we will carefully plan and execute a data collection on the basis of a large ninth-grade secondary school student sample (N = 600) allowing for the application of advanced statistical methods. In this, DynASCEL will pursue innovative avenues that will sustainably broadening the scope of state-of-the-art research in complementing, refining, and challenging current conceptions of ASC as a mere trait-like characteristic.