Prolonged exposure to glucocorticoid stress hormones precipitates mood and cognitive disorders. We identified arginine and glutamate rich 1 (ARGLU1) in a screen for new modulators of glucocorticoid signaling in the CNS. Biochemical studies found that the glutamate rich C-terminus coactivates the glucocorticoid receptor (GR) and the arginine rich N-terminus interacts with splicing factors and RNA. RNA-seq of neuronal cells +/- siARGLU1 found significant changes in the expression and alternative splicing of distinct genes involved in neurogenesis. Loss of ARGLU1 was embryonic lethal in mice, and knockdown in zebrafish caused neurodevelopmental and heart defects. Treatment with dexamethasone, a GR activator, also induced changes in the pattern of alternatively spliced genes, highlighting an underappreciated global mechanism of glucocorticoid action in neuronal cells. Thus, in addition to its basal role, ARGLU1 links glucocorticoid-mediated transcription and alternative splicing in neural cells, providing new avenues from which to investigate the molecular underpinnings of cognitive stress disorders.