Ice cream is a complex multiphase structure consisting of ice, air, and fat as dispersed phases at a range of different length-scales, all embedded in a continuous phase consisting of unfrozen sugar solution known as the matrix or serum. The entire structure is the result of both the ingredients and all the processes used in ice cream manufacture including emulsification, freezing, and aeration. It is thermodynamically unstable and delivered quality can only be assured at low and stable temperatures. Physicochemical processes during storage can lead to loss of quality by coarsening of the ice particles, disproportionation of the air, and the loss of water from the matrix. Product design for specific sensory, stability, shape, and increasingly, nutritional properties, is a challenging task and must take account of all these aspects of the structure. Almost all properties are sensitive to the size, density, and morphology of the dispersed phases as droplets, cells, crystals, or even micelles. Finer structures, in general, result in more desirable organoleptic properties such as creaminess and smoothness but the interfacial dynamics are more rapid, leading to less stability. Even small changes in the relative densities of the dispersed phases such as in the case of low-fat or fat-free products can dramatically change key properties such as taste perception, mouth-feel, and rate of melt. Conventional formulation and processing techniques complemented by the use of specific additives such as emulsifiers and stabilizers enable some control, albeit limited, over the interfacial dynamics and stability. New ingredients and new technologies (such as low temperature extrusion) have been developed to enable higher levels of control on the interfacial behavior either through direct molecular intervention on an interface or new structuring processes wherein interfaces are created in a new or different way. Examples of new ways of influencing the ice, fat, and air interfaces will be discussed such as "ice structuring protein" and hydrophobins. Challenges that remain highlight the need for new types of molecular and microstructural interventions to achieve the next levels in design capability for the ice creams of tomorrow.