Neuropeptides are small molecules that act as messengers between different brain regions. There are roughly 100 neuropeptides that are important for a variety of functions, including hunger, memory, and learning. Oxytocin is one such neuropeptide, playing a crucial role in childbirth and breastfeeding. More recently, oxytocin has been shown to be essential for our social behaviors. When given to people in the form of a nasal spray, oxytocin can change key aspects of social behavior, such as how well we can recognize emotions in others. As people with autism spectrum conditions have difficulties in how social information is understood and used, scientists have been testing oxytocin nasal spray as a potential treatment. But how does oxytocin nasal spray travel from the nose to the brain, and how does it change how we behave socially?