Synapse formation is an essential aspect of brain development. Synaptic dysfunction is a common feature of neurodevelopmental disorders including autism, epilepsy, and schizophenia. Healthy brain development depends on the dynamic interactions of multiple cell types, including neurons, astrocytes, and microglia. It is increasingly clear that immune signaling also impacts the brain, not only in pathology, but during development and homeostasis. For example, our group has shown that cytokine signaling plays key roles in modulating microglial function and synaptic development. In ongoing projects, we continue to use transcriptomics, mouse genetics, and imaging to study neuroimmunity and neuron-glial communication in development, plasticity and behavior.