Flavor molecules belong to different chemical classes, and possess various sensory properties. They are present in the foods, but in order to reach the sensory receptors they have to be released in the saliva during the eating process and for aroma compounds in the air phase from the oral to the nasal cavity. This chapter will present an overview of the different aroma and taste compounds, their dynamic release from the food matrix into the saliva and the oronasal cavity, taking into account the in-mouth physiological process, and the influence on flavor perception. In-mouth flavor compound release and flavor perception are very complex phenomena which are not well understood yet. The properties of the food matrix and oral physiological characteristics and their interactions are the main drivers for interindividual variability. The development of mechanistic models allowed a better understanding of the release of aroma and taste compounds during the eating process. However, the release behavior does not always explain sensory perception, due to other physiological mechanisms at the central and peripheral levels.