A nasal delivery device for and method of delivering particulate substance to the nasal airway of a subject. The delivery device includes a body assembly including a mouthpiece unit which includes a mouthpiece through which the subject in use exhales, and a substance-supply unit which is fluidly connected to the mouthpiece unit and actuatable to provide particulate substance for delivery to the nasal airway of the subject. The body assembly is configured to receive a replaceable nosepiece unit which includes a nosepiece and contains a container containing particulate substance.