We present an overview of a model for the co-evolution of knowledge and event memory. The model, termed SARKAE (Storing and Retrieving Knowledge and Events), describes the development of knowledge and event memories as an interactive process: knowledge is formed through the accrual of individual events, and the storage of an individual episode is dependent on prior knowledge. We reference two experiments which provide data to inform our theory: these studies involve the development of new knowledge, and then testing in transfer tasks involving episodic memory, retrieval from knowledge, and perception. The results of the transfer tasks indicate a substantial role of pure frequency or raw exposure, in opposition to the contextual diversity accounts of frequency suggested by Adelman et al (2006). An overview of the SARKAE model is presented. The model is able to account for the effects of frequency in the absence of contextual diversity.