The paper explores the existence and developmental implications of a negativity bias in early social-emotional development. The authors argue that adults exhibit a negativity bias, showing a greater tendency to attend to, learn from, and use negative information compared to positive information. This bias is hypothesized to serve evolutionary and developmental functions. The paper reviews empirical evidence from various domains, including social referencing, discourse, and memory, to support the presence of a negativity bias in infants and young children. It discusses the ontogenetic mechanisms underlying the emergence of this bias and explores its evolutionary and developmental consequences. The authors suggest that the negativity bias is evident in infant social referencing, where negative cues have a more significant impact on behavior than positive cues. They also find that children's discourse and memories tend to focus more on negative emotions and events, indicating a negativity bias in these areas. The paper concludes by proposing future research directions to further examine the negativity bias in infants and older children.The paper explores the existence and developmental implications of a negativity bias in early social-emotional development. The authors argue that adults exhibit a negativity bias, showing a greater tendency to attend to, learn from, and use negative information compared to positive information. This bias is hypothesized to serve evolutionary and developmental functions. The paper reviews empirical evidence from various domains, including social referencing, discourse, and memory, to support the presence of a negativity bias in infants and young children. It discusses the ontogenetic mechanisms underlying the emergence of this bias and explores its evolutionary and developmental consequences. The authors suggest that the negativity bias is evident in infant social referencing, where negative cues have a more significant impact on behavior than positive cues. They also find that children's discourse and memories tend to focus more on negative emotions and events, indicating a negativity bias in these areas. The paper concludes by proposing future research directions to further examine the negativity bias in infants and older children.