An example of an anti-coalescing agent for a three-dimensional (3D) printing process includes a vehicle and an anti-coalescing polymer dispersed in the vehicle. The vehicle includes a co-solvent, a surfactant, a humectant, and water. The anti-coalescing polymer has a mean particle size ranging from about 50 nm to about 195 nm, and the anti-coalescing polymer is to coat polymeric build material particles to prevent the polymeric build material particles from coalescing during electromagnetic radiation exposure of the 3D printing process.