A memory array comprising strings of memory cells comprises laterally-spaced memory blocks individually comprising a vertical stack comprising alternating insulative tiers and conductive tiers. Operative channel-material strings of memory cells extend through the insulative tiers and the conductive tiers. Upper masses comprise first material laterally-between and longitudinally-spaced-along immediately-laterally-adjacent of the memory blocks and second material laterally-between and longitudinally-spaced-along the immediately-laterally-adjacent memory blocks longitudinally-between and under the upper masses. The second material is of different composition from that of the first material. The second material comprises insulative material. Other embodiments, including method, are disclosed.