Orthographic systems vary dramatically in the extent to which they encode a language’s phonological and lexico-semantic structure. Studies of the effects of orthographic transparency suggest that such variation is likely to have major implications for how the reading system operates. However, such studies have been unable to examine in isolation the contributory effect of transparency on reading because of covarying linguistic or sociocultural factors. We first investigated the phonological properties of languages using the range of the world’s orthographic systems (alphabetic, alphasyllabic, consonantal, syllabic, and logographic), and found that, once geographical proximity is taken into account, phonological properties do not relate to orthographic system. We then explored the processing implications of orthographic variation by training a connectionist implementation of the triangle model of reading on the range of orthographic systems while controlling for phonological and semantic structure. We show that the triangle model is effective as a universal model of reading, able to replicate key behavioral and neuroscientific results. The model also generates new predictions deriving from an explicit description of the effects of orthographic transparency on how reading is realized and defines the consequences of orthographic systems on reading processes. (PsycInfo Database Record (c) 2020 APA, all rights reserved)