The present article describes the application of a theory-based framework to understand current public knowledge of genetic risk factors of multifactorial diseases. The main innovative aspect is the application of E. M. Rogers' knowledge framework which distinguishes three types of knowledge: "awareness knowledge," "how-to knowledge," and "principles knowledge." We argue that distinguishing these types of knowledge allows for a more sophisticated overview of the general public. To illustrate the application of Rogers' framework, we performed a literature review of current public knowledge of genetic risk factors of multifactorial genetic diseases. Relevant articles were identified by searching the Pubmed, Web of Science, Embase, CINAHL, ERIC, and PsycINFO databases from January 1990 until January 2007 and by performing reference list and author searches. Although this review showed that current public knowledge is limited, it also showed that the knowledge framework may be a useful tool for assessing different types of public knowledge and pinpointing flaws or caveats in public knowledge with more precision and subsequently develop public health campaigns to remedy such flaws. Implications for genetic education are discussed.