This chapter addresses the particular constellation in which age-grading emerged as the favored form of grouping schoolchildren. To grasp the complexity of its introduction, institutionalization, and stabilization, the study employs actor-network theory (ANT) with its focus on assemblages and networks. This part elucidates the theoretical configurations and methodological implications of ANT before delineating how this approach can be applied to historical research. By highlighting various historical studies as well as the—thus far—scarce application cases from history of education research, this section presents a possible operationalization of ANT that aids in tracing the assemblies which promoted the emergence and institutionalization of age-grading. The part closes with an exemplary application of the translation process utilized in Chaps. 4 and 5 .