Brain development depends upon close communication between neurons and the specialized cells that support them. These support cells, collectively known as glia, are exquisitely sensitive to stress and other changes in the brain environment and are primary conduits between the immune system and the brain. Importantly, astrocytes and microglia are increasingly implicated in normal synapse formation and remodeling. We combine transcriptomics, mouse genetics, and imaging to study the role of astrocytes and microglia in neural circuit development and brain plasticity. Through the window of normal brain development, we aim to understand how dysfunctional neuron-glia interactions contribute to neuropsychiatric diseases including autism, epilepsy, schizophrenia, and others.