Despite extensive work in the research field of memory culture, two problems persist to this day: the relationship between the individual and the collective remains largely unclear, and too often there is an assumption of the existence of a "true," unaltered memory. The present "Theory of Memory Cultures" offers a solution to these problems by analyzing memory culture as part of the societal knowledge reservoir—systematically in terms of its emergence, structure, and function. It complements the description of human cultural existence as animal symbolicum with the chapter on memory. In doing so, the work brings together the constructivist sociology of knowledge of Peter L. Berger and Thomas Luckmann with the life-world analysis of Alfred Schütz. On this theoretical basis, it systematizes the findings of memory research.