In an example of a three-dimensional printing method, a polymeric build material is applied. A fusing agent is selectively applied on at least a portion of the polymeric build material. The fusing agent includes cesium tungsten oxide nanoparticles, a zwitterionic stabilizer, and an aqueous vehicle. The polymeric build material is exposed to electromagnetic radiation to fuse the portion of the polymeric build material in contact with the fusing agent to form a layer.