A method of forming a vertical string of memory cells comprises forming a lower stack comprising first alternating tiers comprising vertically-alternating control gate material and insulating material. An upper stack is formed over the lower stack, and comprises second alternating tiers comprising vertically-alternating control gate material and insulating material having an upper opening extending elevationally through multiple of the second alternating tiers. The lower stack comprises a lower opening extending elevationally through multiple of the first alternating tiers and that is occluded by occluding material. At least a portion of the upper opening is elevationally over the occluded lower opening. The occluding material that occludes the lower opening is removed to form an interconnected opening comprising the unoccluded lower opening and the upper opening. Charge storage material is deposited into the interconnected opening for the charge storage structures for the memory cells of the vertical string that are in each of the upper and lower stacks and thereafter tunnel insulator and channel material are formed into the interconnected opening for the memory cells of the vertical string that are in each of the upper and lower stack. Other embodiments are disclosed, including embodiments independent of method.