Language is important for emotion perception, but very little is known about how emotion labels are learned. The current studies examine how preverbal infants map novel labels onto facial configurations. Across studies, infants were tested with a modified habituation paradigm ("switch design"). Experiments 1 and 2 found that 18-month-olds, but not 14-month-olds, mapped novel labels ("blicket" and "toma") to human facial configurations associated with happiness and sadness. Subsequent analyses revealed that vocabulary size positively correlated with 14-month-olds' ability to form the mappings. Experiment 3 found that 14-month-olds were able to map novel labels to facial configurations when the visual complexity of the stimuli was reduced (i.e., by using cartoon facial configurations). This suggests that cognitive maturation and language development influence infants' associative word learning with facial configurations. The current studies are a critical first step in determining how infants navigate the complex process of learning emotion labels. Keywords Language. Infancy. Emotions. Word learning Language is important for emotion perception in early childhood (Ruba, Meltzoff, & Repacholi, 2020b). The ability to label facial configurations is both an index of emotion understanding (Pons, Harris, & de Rosnay, 2004) and a predictor of social and academic competence (Izard et al., 2001). Consequently, much research has focused on when children learn different emotion labels. This is a gradual process that begins late in the second year of life and continues throughout early childhood (Widen, 2013). However, relatively little is known about how emotion labels are learned (see Hoemann,