The relation of domain knowledge to achievement, and changes in this relation that occur with age and type of memory task, are discussed. First, different mechanisms through which domain-specific knowledge relates to strategy use in memory tasks are summarized. Then, empirical evidence that indicates direct effects of the knowledge base on memory performance is discussed in detail. The core assumption is that developmental improvements in memory performance may be due predominantly to development and application of the knowledge base, rather than to development of strategic competence. Research based on the expert-novice paradigm that illustrates this point particularly well receives special attention. Special attention is also given to developmental studies that concentrate on the influence of a highly articulated knowledge base on memory performance. Empirical findings based on the expert-novice paradigm are used to: (1) compare the knowledge structure and memory performance of experts and novices of different ages; (2) compare the knowledge representation of younger and older experts; and (3) explore the relation of individual differences in general intellectual abilities to the acquisition and use of domain-specific knowledge. A total of 44 references are cited. (RH)