The invention includes capacitors, capacitor forming methods, field effect transistors, and field effect transistor forming methods. In one aspect, a method of forming a layer including tungsten oxide includes forming a first layer including tungsten nitride over a substrate. In one implementation, the tungsten nitride is oxidized under conditions effective to form a second layer at least a majority of which is tungsten trioxide. In one aspect, a capacitor forming method includes forming a first capacitor electrode layer over a substrate. A second layer including tungsten nitride is formed over the first capacitor electrode layer. A third capacitor electrode layer is formed over the second layer. The second layer is oxidized under conditions effective to transform at least some of the tungsten nitride into a tungsten trioxide comprising capacitor dielectric layer. Other capacitor forming methods are contemplated. The invention also includes capacitors formed by these and other methods. In one aspect, a method of forming a field effect transistor includes forming a tungsten nitride comprising layer proximate at least one of a semiconductive channel region or a conductive gate layer. The tungsten nitride comprising layer is oxidized under conditions effective to transform at least some of the tungsten nitride to a tungsten oxide comprising gate dielectric layer. A transistor gate is provided operably proximate the gate dielectric layer, and source/drain regions are provided operably proximate the transistor gate.