Some embodiments include memory arrays having a plurality of memory cells vertically between bitlines and wordlines. The memory cells contain phase change material. Heat shields are laterally between immediately adjacent memory cells along a bitline direction. The heat shields contain electrically conductive material and are electrically connected with the bitlines. Some embodiments include memory arrays having a plurality of memory cells arranged in a first grid. The first grid has columns along a first direction and has rows along a second direction substantially orthogonal to the first direction. First heat shields are between adjacent memory cells along the first direction and are arranged in a second grid offset from the first grid along the first direction. Second heat shields are between adjacent memory cells along the second direction, and are arranged lines in lines extending along the first direction. Some embodiments include methods for forming memory arrays.