Current research in developmental psychopathology has emphasised how emotion dynamics, such as affective variability, relate to psychosocial functioning. In this brief article, we examined mean differences in mothers' and adolescents' affective intensity and lability in positive and negative emotions and explored how these emotion dynamics related to depressive symptoms and mother-adolescent relationship quality. We administered individual surveys each day for one week to mother-adolescent dyads (N = 109) that inquired about positive and negative affective states. Affective intensity was measured by the mean across the week and lability by the standard deviation. Participants also reported on their depressive symptoms and adolescents reported on relationship quality. Results showed that positive affect was more intense and more variable than negative affect, and adolescents experienced more intense negative affective and less intense positive affect than mothers. Greater mother and adolescent negative affect intensity and less maternal positive affect intensity related to more depressive symptoms. Affective intensity in mothers and adolescents and affective lability in mothers related to mother-adolescent relationship quality. These findings extend the growing body of knowledge on individuals' affective intensity and variability by considering family dynamics.