Referring to the ongoing discussion about the meaning of Cultural-historical Psychology I will defend two theses: (1) Activity Theory is a methodology; (2) The core of what is called the Cultural Historical School is its specific methodology. Because in English speaking countries the term “methodology” commonly covers the sum of scientific methods, techniques, and procedures, I will try to explain his understanding of methodology – following E.G. Judin – as a historically developed complex comprising four different levels of knowledge, of which the fundamental basis and principal level is philosophical knowledge, although these philosophical principles may never be directly applied or transferred to the level of concrete scientific disciplines.