Recent research has highlighted the important role parents can play in facilitating adolescents' adjustment with their friends. To do so, however, parents need to have insight into their children's social difficulties. Yet past research has shown that parents as a group are not particularly accurate at gauging children's social problems and concerns. However, very few studies have looked closely at variability from parent to parent in this skill. This study examines mothers' abilities to anticipate children's vulnerability to jealousy over friends. It was hypothesized that mothers would vary in their ability to accurately anticipate the circumstances that make their adolescent jealous and that this variability would relate in systematic ways to aspects of the mother, the child, and their relationship. Consistent with some past research, as a group, mothers' judgments of their child's jealousy was not highly correlated with what children reported. Nonetheless, wide variability in accuracy existed across mothers. Regression analyses indicated that mothers' proneness to romantic jealousy was not an important predictor of their accuracy, but mothers of emotionally expressive children and mothers with close relationships with their children were more accurate than were mothers of children who inhibited their emotions or mothers who had less close relationships. In turn, when their mothers were more accurate, adolescents had closer friendships, less aggressiveness with peers, higher social self-esteem, and less loneliness. Results caution against broad generalizations about maternal accuracy and support efforts to better understand why some mothers are more effective social coaches of their children than are others.