BAF53B also known as ACTL6B is a family member of actin-related proteins (ARPs), which share significant amino acid sequence identity to conventional actins. BAF53B regulate nucleosome positioning and chromatin accessibility. BAF53B supports transcriptional programs required for neuronal differentiation, dendritic and synaptic maturation, and activity-dependent gene regulation by coordinating with other BAF components to modulate enhancer and promoter usage. Through these epigenetic functions, ACTL6B is linked to pathways controlling neurodevelopmental timing, neuronal connectivity, and plasticity. Genetic and functional perturbations of ACTL6B/BAF53B have been associated with neurodevelopmental disorders and altered neuronal gene expression states relevant to models of cognitive and behavioral phenotypes.