One of the arguments that explain the relevance of this book is the overwhelming lack of knowledge that the current literature throws on the Inhelderian microgenetic method. The place of this method is definitely ungrateful and has remained incomprehensibly hidden. All indications are that it seems to have lagged behind many of the brightest heads in developmental psychology, those who made up the Geneva school. The book aims to illustrate how Inhelderian microgenesis emerges in the landscape of cognitive development as a new object of study. More than ruptures with respect to the problems of the normative subject, the Inhelderian project entails both conceptual and methodological displacements. In this new map, the psychological subject takes a predominant place, and does so in terms of the cognitive functioning of the subject in relation to situations of resolution. This functioning is studied on the basis of the microgenetic method, which makes it possible to identify the role of mental schemas, their combinations and recompositions in the face of specific and problematic situations. The totally original version of the microgenetic method that is delivered from the Inhelderian legacy in this book, not only recovers its basic sense but also advances in the direction of some indications that Inhelder herself had pointed out. This renewed object of study recovers a subject, with a status in terms of its own models, its theories and its dynamics. Starting from a demanding and knowledgeable reading of Inhelder's work. This knowledge becomes the best criterion to point out an updated path of the work with concepts and tools resulting from recent research but articulated with a microgenetic vision coming from the most orthodox tradition. The bet consists of advancing from the legacy of Inhelder and her team and projecting it as a methodological alternative for current research in developmental studies.