The physical properties of emulsions such as stability, theology, sensory and optical characteristics or mass-transfer kinetics are largely influenced by their characteristic microstructure. The interrelationship between properties and microstructure is called the property function. The desired microstructure may be attained by establishing suitable process conditions; the link between the two is described as the process function. Essential structure parameters, besides the dispersed phase fraction, are droplet size and droplet size distribution of the internal phase. The distribution of the dispersed phase of an emulsion, for example, depends on the intensity and mechanism of droplet disruption and on the extent of superimposed or subsequent coalescence in the apparatus. Droplet disruption IS function of equipment characteristics and energy input per volume. This concept of energy density, an example of an explicit process function, may serve as a useful tool for those concerned with the designing and scaling-up of mechanical emulsification processes in practice. The rate of droplet coalescence, determined using a novel method, depends on the stabilizing properties of the emulsifier, but may also be influenced by process parameters. Various examples are presented to show how to change emulsion properties by property and process functions. By the example of formulating solubilized free phytosterols poorly soluble in water and oil, the significant effect of a properly adjusted microstructure will be demonstrated.