Understanding why the human visual cortex is organized into functionally specialized regions is one of the central open questions in cognitive neuroscience. While decades of research have documented selective responses for faces, bodies, and scenes, we still lack a principled account of why certain visual categories recruit specialized neural circuitry while others do not. Existing approaches have largely relied on contrast-based neuroimaging and descriptive accounts of selectivity, leaving unresolved whether functional specialization reflects computational constraints, developmental input statistics, or intrinsic neural biases. DEEPFUNC addresses this gap by introducing a unified computational–neuroscientific framework to explain the origins of functional specialization. Focusing on the human ventral visual pathway, the project combines large-scale natural visual input, hypothesis- and data-driven analyses, deep neural networks, and behavioral and neural data. This integrative approach allows us to move beyond descriptive mapping toward mechanistic explanation. The project is structured around three core objectives. First (WP1 – What), we will precisely characterize which properties of visual categories give rise to functional specialization. Second (WP2 – How), we will determine how natural visual input statistics and experience shape the development of specialization. Third (WP3 – Why), we will identify the computational and feature-level principles that determine where and why specialized representations emerge in human visual cortex. By systematically linking deep neural networks with human neuroimaging and behavior, DEEPFUNC establishes a testable computational account of functional specialization. This framework enables us to evaluate competing hypotheses, generate falsifiable predictions, and uncover principles that generalize beyond vision. The expected impact of DEEPFUNC is threefold. Scientifically, it advances the field from descriptive characterization to mechanistic explanation of functional specialization. Methodologically, it provides scalable tools for analyzing and comparing biological and artificial neural systems. Conceptually, it informs the design of intelligent machines by identifying when and why specialized processing architectures are advantageous. More broadly, clarifying how and why the brain organizes information into specialized systems contributes to a deeper understanding of the architecture of the human mind and brain.