There are surprisingly few theories of the normal development of literacy that take into account the different cognitive processes underlying reading and spelling skills. The present framework suggests three phases, corresponding to the acquisition of logographic, alphabetic, and, finally, orthographic skills. At each phase, a new skill is introduced with either reading (input processes) or writing (output processes) acting as pacemaker. This stepwise progress is driven by a certain opposition between reading and writing processes. At any of the critical points where a new step has to be taken, breakdown can occur. This will result in different types of literacy disorder. However, the disorder will not only be characterized by the deficiency in a particular skill, but also by compensatory skills which will inevitably develop. Only by using models of this type will we be able to achieve a properly developmental perspective for developmental dyslexia.