A new study shows that a candidate schizophrenia pathway, neuregulin-1–ErbB4 signaling, inhibits Src-mediated enhancement of synaptic N-methyl-D-aspartate receptor (NMDAR) function (pages 470–478). These results suggest that Src can have a pivotal role in NMDAR hypofunction in schizophrenia and thus might have potential therapeutic implications for this complex neuropsychiatric disorder.