A method used in forming an electronic device comprising conductive material and ferroelectric material comprises forming a composite stack comprising multiple metal oxide-comprising insulator materials. At least one of the metal oxide-comprising insulator materials is between and directly against non-ferroelectric insulating materials. The multiple metal oxide-comprising insulator materials are of different composition from that of immediately-adjacent of the non-ferroelectric insulating materials. The composite stack is subjected to a temperature of at least 200° C. After the subjecting, the composite stack comprises multiple ferroelectric metal oxide-comprising insulator materials at least one of which is between and directly against non-ferroelectric insulating materials. After the subjecting, the composite stack is ferroelectric. Conductive material is formed and that is adjacent the composite stack. Devices are also disclosed.