Infancy is a period of significant change for both the brain and behavior. During the first two years of life, the brain experiences an explosion of synaptic connections and myelination, alongside rapid development in motor, linguistic, and social behavioral abilities. Understanding the relationship between brain development and behavioral outcomes can provide insight into critical periods and early indicators of developmental delays. One brain region that plays a crucial role during this time and is closely linked to various behavioral domains is the cerebellum. In this study, we explored the cerebellum's potential influence on behavioral outcomes at 18 months of age. We utilized the developing Human Connectome Project (dHCP) dataset, an open-source neuroimaging resource that includes MRI scans at birth and a behavioral assessment at 18 months. We analyzed the diffusion-weighted MRI scans using Neurite Orientation Dispersion and Density Imaging (NODDI), allowing us to approximate neuronal morphology within the cerebellum. These NODDI metrics were then incorporated into a generalized additive model (GAM), revealing that we could predict 3% to 6% of the variance in motor and language outcomes. Our findings suggest that the composition of specific cerebellar lobules at birth, such as right VIIIa and left V, is important for the development of expressive language, as well as fine motor skills. This highlights the cerebellum's role as a key hub in the development of motor and language functions from birth. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]