Ice cream has a very complex structure, with multiple phases that can influence product textural quality and physical attributes including shape retention and structural collapse during melting. The mix ingredients supply water, fat, milk solids-not-fat (casein micelles, whey proteins, lactose, and milk salts), sugars (sucrose and partially hydrolyzed starch, including glucose, maltose and higher saccharides), stabilizers, and emulsifiers. Air is subsequently added prior to dynamic freezing. All of these contribute to the structural elements in ice cream. Fat either remains as globular, emulsified droplets, or is converted to a partially-crystalline, agglomerated fat structure, a process that is enhanced by the action of the emulsifiers at the fat globule interface. Water is converted to ice crystals. Air is whipped into small bubbles. The sugars and stabilizers become freeze-concentrated in the unfrozen serum phase. Proteins contribute to fat and air structures by adsorbing to interfaces and to the unfrozen phase by providing bulk and water holding properties, both of which add viscosity. Protein polysaccharide interactions can also occur. This chapter reviews the formation and significance of these structural elements. It also discusses the effect of these structures on physical properties of ice cream, including thermal, meltdown, and rheological/mechanical properties.