Polyelectrolyte microcapsules, and methods for making and using the polyelectrolyte microcapsules, are described. A method of making polyelectrolyte microcapsules includes forming an “interfacial complexation in emulsion” (ICE), wherein a polyelectrolyte “shell” is formed by complexing two different polyelectrolytes together at an interface between two immiscible fluids. Both hydrophilic and hydrophobic materials can be incorporated into the cores and shells of the polyelectrolyte microcapsules.