Cultural-historical activity theory, as A. N. Leont'ev articulated it, has received an exponentially growing interest over the past several decades, especially in the version in which the theory has been taken up in the Anglo-Saxon literature through the work of Y. Engeström. Whereas the theory has proven to be fruitful, providing a framework to those scholars interested in understanding human knowing and learning from a more holistic perspective, essential aspects of the original theory have either not been taken up or have been transformed in the take up. In part, the problems arise from the difficulties of translating Leont'ev-as the work of Marx on which the theory is builtinto English, where several originally distinct pairs of (Russian, German) categories and concepts are conflated into one (English). As a result, the full potential of the theory has not been achieved. The purpose of this article is to bring into the foreground some of the fundamental aspects of cultural-historical activity theory that have disappeared during translation and uptake into Anglo-Saxon scholarship. Cultural-historical activity theory-as A. N. Leont'ev (1983) originally framed it and as subsequently taken up in the Anglo-Saxon scholarship through the work of Y. Engeström (e.g., 1987)-has received exponentially increasing interest over the past 25 years (Roth, 2004; Roth & Lee, 2007). Explicitly grounded in dialectical materialism (Marx/Engels, 1962), cultural-historical activity theory is a process theory for understanding the human life form generally, and its concrete manifestations in human activity more specifically. In the translation from Marx's German and Leont'ev's Russian, some of the most interesting, key aspects have disappeared and are unavailable to Anglo-Saxon scholars who read Activity, Consciousness, Personality (A. N. Leont'ev, 1978). Leont'ev summarizes the core message of this book as an effort "to psychologically comprehend those categories that are essential for the construction of a consistent system of psychology as a concrete science of the emergence, functioning, and structure of the psychological reflection of reality, which mediates the life of individuals" (A. N. Leont'ev, 1983, p. 99). These fundamental categories, minimum units that retain the characteristics of the whole-i.e., society as a self-moving, internally contradictory entity mediating all of its parts-include "the category of object-oriented activity, the category of human consciousness, and the category of personality" (p. 99). The purpose of this article is to bring into the foreground some of the fundamental aspects of cultural-historical activity theory that have disappeared during translation and uptake into Anglo-Saxon scholarship. I begin with a concrete example of multi-leveled developmental change, which I subsequently use in the theoretically oriented parts of this paper. I conclude with a call for a re/orientation on the fundamental, currently underused aspects of cultural-historical activity theory.