A memory array comprising strings of memory cells comprises a conductor tier comprising conductor material. Laterally-spaced memory blocks individually comprise a vertical stack comprising alternating insulative tiers and conductive tiers. Channel-material strings of memory cells extend through the insulative tiers and the conductive tiers. Conducting material of a lowest of the conductive tiers directly electrically couples together the channel material of individual of the channel-material strings and the conductor material of the conductor tier. An uppermost portion of the conductor material comprises conductively-doped semiconductive material that is directly against the conducting material, of different composition from that of the conducting material, and comprises at least one of carbon, nitrogen, oxygen, metal, and n-type conductively-doped semiconductive material also comprising boron. Other embodiments, including method, are disclosed.