An electrode assembly for neuro-cranial stimulation includes an electrode, a conductive gel, and an adapter including an interior compartment for positioning the electrode relative to the adapter and for receiving and retaining the conductive gel. The conductive gel contacts the electrode along an electrode-gel interface. An orifice at one end of the interior compartment and adjacent to a positioning surface of the adapter for positioning the electrode assembly against a skin surface of a user enables the conductive gel is able to contact the skin surface of the user to define a gel-skin interface, such that a minimum distance between the electrode-gel interface and the gel-skin interface is maintained between 0.25 cm and 1.3 cm. An electrode assembly mounting apparatus is provided for adjustably positioning a plurality of electrode assemblies against target positions on the cranium.