The preschool years are a critical period of brain and language development, although little research has investigated relationships between language and brain structure or function during this age. This thesis contains an investigation of children aged 3.0-4.7 years who underwent assessments of phonological processing and speeded naming, measures that predict later reading ability. We used quantitative MRI methods to investigate brain structure and function, including diffusion tensor imaging, inhomogeneous magnetization transfer imaging, morphological analysis, and arterial spin labeling. Findings suggest that children with stronger language skills possess more mature patterns of brain structure and function. Our results are consistent with previous research in older children that suggest that structural and functional markers for reading disability exist before children begin formal reading instruction. Our results have identified neurological markers for children at risk for developing reading impairments, including reduced myelination, decreased cortical thickness, and reduced perfusion in the left hemisphere.