Although reading fluency plays a crucial role in reading comprehension, little is known about its early development. In this study, we first aimed to replicate Hudson et al.'s (2009, 2012) model of reading fluency development among beginning readers and, second, to expand it by incorporating components of articulation rate, sub-lexical orthographic knowledge, and reading accuracy, all of which are theoretically linked to reading fluency development. Three hundred and thirty English-speaking Grade 1 students (51.5% female; M = 74.82 months; SD = 3.60) were assessed at three time points (September [T1], January [T2], and May [T3]). At T1, we administered measures of rapid automatized naming (RAN), processing speed, phonemic blending fluency, and letter-sound fluency, at T2, measures of phonogram fluency and sub-lexical orthographic knowledge, and, finally, at T3, word reading fluency, nonword reading fluency, and text reading fluency. Using path analysis, we tested three models: a baseline model based on Hudson et al.'s model and two expanded models that included the additional measures. Our results replicated the core relations proposed by Hudson et al. and further demonstrated significant contributions from sub-lexical orthographic knowledge and reading accuracy to text reading fluency through word reading fluency. These findings are consistent with theoretical frameworks such as Ehri's (2014) orthographic mapping framework and the lexical quality hypothesis (Perfetti, 2007), showing the contributions but also limitations of the components of the reading fluency model.