ABSTRACT Flavor is perhaps the most important determinant of eating habits—we eat foods that taste good and avoid foods that taste bad. Because eating habits are directly linked to nutrition and health, altering flavor perception is a prime target for interventions aimed at steering people toward heathier food choice. Flavor includes well-understood gustatory qualities (sweet, bitter, sour, salty, umami). However, a substantial portion of flavor constitutes olfactory (smell) qualities (try taking a sip of wine or eating a jellybean candy while pinching your nose). The gustatory and olfactory sensory systems that contribute to flavor each have unique characteristics. Hedonic perception of gustatory signals is innate and relatively stable (e.g., from birth into adulthood, sweet is liked, bitter disliked). In contrast, olfactory processing tends to be highly plastic, suggesting a strong opportunity to alter flavor perception through interventions. This proposal will gain basic understanding of the relationship between flavor-related odor perception and eating habits. I focus on children 4-6 years of age, because this constitutes a developmental period during which eating habits are formed for life, making it a particularly promising target for interventions. In Specific Aim 1, I will characterize the contribution of olfaction to multiple aspects of flavor perception in children and adults using a novel adaptation of a simple, non-verbal rating procedure, as well as analysis of video recordings of facial expressions. Preliminary data suggest that perception of olfactory flavor components (but not gustatory flavor components) undergoes substantial developmental changes. I will determine the extent to which differences in smell perception between children and adults can be explained by exposure to specific foods, as measured by a modified food frequency questionnaire and a non-verbal identification task. In Specific Aim 2, I will determine how individual differences in flavor perception among children relate to weight status. In order to development effective nutritional interventions, we must consider the relationship between weight status and flavor perception. Although this relationship has not been examined among young children, there is substantial evidence that overweight/obesity is associated with impairments in flavor sensitivity among adults. By conducting a regression analyses between BMI-for-age and perceptual measures for taste and smell, I will be able to determine whether this relationship emerges as early as ages 4-6. The results will provide novel mechanistic insight into how sensory processing interacts with flavor exposure and weight status during early childhood.