Autism spectrum disorder (ASD) is diagnosed when individuals exhibit characteristic behaviors, decreased social interactions, and impaired communication. Curiously, many with ASD also suffer from gastrointestinal issues, like abdominal cramps and constipation. Guided by this co-occurrence of brain and gut problems, researchers are investigating a bacterium that alleviates GI and behavioral symptoms in autistic-like mice, introducing a potentially transformative probiotic therapy for autism and other neurodevelopmental disorders.