Olfaction remains scarcely studied in humans (McGann, 2017). However, it is one of the first senses to develop in utero (Schaal, 1988). This sense participates in danger detection, feeding, emotional regulation but also in social interactions (Macfarlane, 1975; Mennella & Beauchamp, 1991; Nicklaus & Rigal, 2010; Delaunay-El Allam et al., 2010) as well as in cognitive development (Schaal, 1997). Olfactory discrimination skills have been demonstrated in young children (Macfarlane, 1975; Doty, 1991). However, no one has ever explored the development of a response to a change in congruence between object and odorant in infants and children between 6 months and 3 years of age. The aim of this study is to construct a behavioral observation situation that can account for the olfactory discrimination skills of young preschoolers from 6 months to 3 years of age.