Maternal singing is considered vital to infant well-being. This study focuses on vocal emotion expressions in infant-directed singing among mothers in war conditions. It examines the questions: (a) how traumatic war events and mental health problems are associated with the content and valence of vocal emotion expressions and (b) how these emotion expressions are associated with infant development. The vocal material consists of songs sung by 50 Palestinian mothers who participated at delivery (T1) as well as when their infants were 6 (T2) and 18 (T3) months of age. These mothers reported traumatic war events (T1); depressive and post-traumatic stress disorder (PTSD) symptoms (T2-T3); and infants' emotional, sensorimotor, and cognitive development (T2-T3). Student judges evaluated the valence and content of vocal emotion expressions in maternal infant-directed singing (playfulness-vivacity, fear, joy, sadness, love-tenderness, anger, and tension). Severe traumatic war events and depressive symptoms were associated with low positive and high negative vocal emotion expressions. High levels of playfulness and joy, as well as low levels of fear and tension, were associated with infant positive affectivity, while low levels of fear, anger, and tension were associated with advanced infant language skills. Discussion focuses on the vocal markers of maternal mental health and infant development.