BACKGROUND: In humanitarian settings, family-level drivers of mental health are insufficiently documented; we examined the strength of caregiver-child associations with two-wave, family-level Afghan data. METHODS: We recruited a gender-balanced sample of 681 caregiver-child dyads (n = 1,362 respondents) using stratified random-sampling in government schools in Kabul (364 dyads) and refugee schools in Peshawar (317 dyads). One year after baseline, we re-interviewed 64% of Kabul and 31% of Peshawar cohorts (n = 331 dyads, 662 respondents), retaining fewer Peshawar families due to refugee repatriation. In multivariable analyses adjusted for baseline, we assessed the extent to which caregiver mental health (Self-Report Questionnaire, SRQ-20) was associated with child symptom scores of post-traumatic stress (Child Revised Impact of Events Scale, CRIES), depression (Depression Self-Rating Scale, DSRS), psychiatric difficulties, impact, and prosocial strength (Strength and Difficulties Questionnaire, SDQ). RESULTS: Caregiver mental health was prospectively associated with all eight measures of child mental health at follow-up, adjusted for baseline. For post-traumatic stress, caregiver mental health had a predictive impact comparable to the child experiencing one or two lifetime trauma events. For depression, caregiver mental health approached the predictive impact of female gender. Thus a one SD change in caregiver SRQ-20 was associated with a 1.04 point change on CRIES and a 0.65 point change in DSRS. For multi-informant SDQ data, caregiver-child associations were strongest for caregiver ratings. For child-rated outcomes, associations were moderated by maternal literacy, a marker of family-level dynamics. Both adults and children identified domestic violence and quality of home life as independent risk and protective factors. CONCLUSIONS: In the context of violence and displacement, efforts to improve child mental health require a thoughtful consideration of the mental health cascade across generations and the cluster of adversities that impact family wellbeing. We identify culturally meaningful leverage points for building family-level resilience, relevant to the prevention and intervention agenda in global mental health.