Although ample research links social factors and suicidality, there remains a gap in understanding how distinct processes within social communication relate to suicidality. We demonstrate how reciprocity of eye-gaze and facial expressions of happiness differ during parent-adolescent conflict based on adolescents’ future suicidal ideation (SI). Facial affect analyses were based on 103 girls (ages 11–13; M = 12.28; 75% White) and their parents. Eye-gaze analyses were conducted in subset of these dyads (N = 70). Participants completed a conflict discussion during which gaze to their partners’ eyes was assessed using mobile eye-tracking glasses and facial affect was coded using FaceReader Observer XT. Adolescents’ SI was assessed 12-months later. Actor-partner interdependence models tested whether participants’ gaze and affect predicted their own and their partners’ gaze and affect one second later and if these intra and interpersonal dynamics differed based on adolescents’ future levels of SI. Girls from dyads with less parental reciprocity of eye-gaze and happiness reported higher levels of SI 12-months later. During early adolescence, girls whose parents reciprocate their eye-contact or positive affect less during conflict may be at heightened risk for SI. If replicated, social communication could provide a promising intervention target to reduce suicidality prospectively.