This article summarizes our research on the manifestation of dyslexia in German and on cognitive deficits, which may account for the severe reading speed deficit and the poor orthographic spelling performance that characterize dyslexia in regular orthographies. An only limited causal role of phonological deficits (phonological awareness, phonological STM, and rapid naming) for the emergence of reading fluency and spelling deficits is inferred from two large longitudinal studies with assessments of phonology before learning to read. A review of our cross-sectional studies provides no support for several cognitive deficits (visual-attention deficit, magnocellular dysfunction, skill automatization deficit, and visual-sequential memory deficit), which were proposed as alternatives to the phonological deficit account. Finally, a revised version of the phonological deficit account in terms of a dysfunction in orthographic-phonological connectivity is proposed. (Contains 3 figures.)