A nasal delivery device for and method of delivering a substance, preferably comprising oxytocin, non-peptide agonists thereof and antagonists thereof, preferably as one of a liquid, as a suspension or solution, or a powder, to the nasal airway of a subject, preferably the posterior region of the nasal airway, and preferably the upper posterior region of the nasal airway which includes the olfactory bulb and the trigeminal nerve, and preferably in the treatment of neurological conditions and disorders.