In one aspect, the invention includes an isolation region forming method comprising: a) forming an oxide layer over a substrate; b) forming a nitride layer over the oxide layer, the nitride layer and oxide layer having a pattern of openings extending therethrough to expose portions of the underlying substrate; c) etching the exposed portions of the underlying substrate to form openings extending into the substrate; d) after etching the exposed portions of the underlying substrate, removing portions of the nitride layer while leaving some of the nitride layer remaining over the substrate; and e) after removing portions of the nitride layer, forming oxide within the openings in the substrate, the oxide within the openings forming at least portions of isolation regions. In another aspect, the invention includes an isolation region forming method comprising: a) forming a silicon nitride layer over a substrate; b) forming a masking layer over the silicon nitride layer; c) forming a pattern of openings extending through the masking layer to the silicon nitride layer; d) extending the openings through the silicon nitride layer to the underlying substrate, the silicon nitride layer having edge regions proximate the openings and having a central region between the edge regions; e) extending the openings into the underlying substrate; f) after extending the openings into the underlying substrate, reducing a thickness of the silicon nitride layer at the edge regions to thin the edge regions relative to the central region; and g) forming oxide within the openings.