The ability to recognize faces, which is critical for everyday social interactions, improves from childhood to adulthood. In adults, face recognition is mediated by a series of regions in the ventral aspect of human occipital and temporal cortex, constituting the ventral face network. The selectivity and spatial extent of the ventral face network develop from childhood to adulthood, in correlation with age-related improvements in face recognition. However, the neural mechanisms of this development, the rate of development, and the relation among factors that govern this development are not well understood. The goals of the proposed research are to fill these substantial gaps in knowledge by determining the relationship between anatomical and functional brain development and understanding how these developments ultimately lead to improved behavior. To achieve these goals, the research will combine cross-sectional and longitudinal measurements in children (5-10 years old) and adults (23-28 years old) obtaining innovative multimodal measurements of functional magnetic resonance imaging (fMRI), quantitative MRI (qMRI), diffusion weighted imaging (DWI), and behavior in each participant. Aim 1 will employ longitudinal measurements of fMRI, qMRI, and face recognition behavior to determine what is the rate of the development of gray matter and functional selectivity in the face network, if development of gray matter and function occur together or one precedes the other, and if neural developments correlate with behavioral improvements in face recognition. Aim 2 will employ cross-sectional and longitudinal measurements using fMRI, DWI, qMRI, and behavior to determine if and how white matter properties of the face network develop, if white matter developments are linked with either functional or behavioral development, and if development of white matter and function occur together or in sequence. Aim 3 will use fMRI and population receptive field (pRF) modeling to determine if and how pRFs in the ventral face network change from childhood to adulthood, and if development of pRF properties is related to fixation patterns on faces. Aim 4 will test if neural responses in face-selective become less sensitive to face transformations from childhood to adulthood, consequently improving generalization across different instances of the face under different sizes or views. Critically, in each aim we will examine not only the development of the ventral face network but the development of the human ventral visual stream more broadly to elucidate the specificity of developmental effects. Overall, the proposed research will advance understanding of neural mechanisms underlying the development of face recognition, it will elucidate completing developmental theories regarding the relation between anatomical and functional brain development, and will provide the first measurements of the developmental rate of multiple facets of human ventral temporal cortex anatomy and fun...