Sperry’s code reimaged? A neuron–astrocyte cadherin code directs astrocyte specialization. (A) δ-Catenin facilitates surface localization and binding of N-cadherin between astrocytes and neighboring deep-layer neurons, and in turn, drives astrocyte morphogenesis. (B and C) In mouse, cortical layers display regionalized differences in neuronal identity and astrocyte morphology. Neuronal N-cadherin serves as a local cue to drive the distinct morphology of deep-layer astrocytes, suggesting that neuronal cadherins may represent the keys that unlock layer-specific astrocyte morphologies.