Emotion concepts are the internally held representations of what defines any given emotion. Contemporary emotion theories posit that emotion concepts occupy a central role in shaping our perceptions and experiences of emotion. However, like other concepts, emotion concepts actively change over the life course. Here, we review classic and contemporary ideas, and recent empirical research, that concern how emotion concepts develop from childhood to adulthood. Emerging evidence suggests that emotion concepts change in complex ways across early life development, which has a tangible impact on the emotional experiences of children, adolescents, and adults. Charting emotion concept development in this way holds implications for basic theories of emotion and development as well as more clinical theories focused on helping children and adolescents overcome emotion-regulatory challenges.