In this theoretical review, evidence for the link between spoken and written word knowledge is summarised, highlighting the specific hypotheses posed in this field and the extent to which they are informative regarding causation. A brief overview of major theories of orthographic learning draws attention to how each characterises the role of oral vocabulary within the learning process, and the timing of its influence. The theoretical foundations and evidence for two cognitive mechanisms that seek to explain the relationship between spoken and written word knowledge are outlined, drawing attention to a key difference between them: the proposed timing of the effect. "Set for variability" (or "mispronunciation correction") is thought to operate from the point of visual exposure, while "orthographic skeletons" are thought to exert an influence on written word learning that begins before exposure to written words. The review closes with a discussion of directions for future research.