A microelectronic device comprises a memory array region, a control logic region, and an additional control logic region. The memory array region comprises a stack structure comprising vertically alternating conductive structures and insulating structures, and vertically extending strings of memory cells within the stack structure. The control logic region underlies the stack structure and comprises control logic devices configured to effectuate a portion of control operations for the vertically extending strings of memory cells. The additional control logic region overlies the stack structure and comprises additional control logic devices configured to effectuate an additional portion of the control operations for the vertically extending strings of memory cells. Methods of forming a microelectronic device, and additional microelectronic devices and electronic systems are also described.