PROJECT SUMMARY. Achieving optimal child socioemotional and cognitive development (SECD) is a global public health priority. Poor development has been linked to low educational attainment, low wage earnings, and poor adult health. Promoting optimal child SECD outcomes necessitates engaging key caregivers, but the majority of psychosocial interventions to promote child SECD target mothers and fail to incorporate a family systems approach. Across cultural contexts, grandmothers are often key advisors or decision-makers on maternal and child health issues. Despite their influential roles, grandmothers are often omitted from interventions and this exclusion can lead to diminished intervention impacts. Understanding how grandmothers’ roles evolve, impact child outcomes, and shape household practices in early life is essential to informing interventions. Further, conflicts between mothers and grandmothers, two key caregivers in early life, may lead to suboptimal caregiving practices and ultimately, poor child SECD. Research is limited on how the grandmother- mother relationship quality affects household caregiving practices, especially in low-resource contexts. The goal of this proposed predoctoral Diversity Supplement is to prepare the applicant for a successful transition to a postdoctoral fellowship, and ultimately an independent investigator career, with a focus on designing, implementing, and evaluating interventions to promote optimal child SECD. This will be accomplished by individualized mentorship and didactic training to: 1) develop new skills in intervention development and implementation science, 2) strengthen professional development skills, specifically in oral and written communication, dissemination, and grant-writing, and 3) successfully apply and transition into a postdoctoral fellowship. The outstanding mentorship team provides complementary and interdisciplinary expertise to support and prepare the applicant for transition from predoctoral to postdoctoral training. The goals of the proposed mixed methods dissertation research are to (1) estimate associations between grandmother involvement across early life and child SECD at age 6, (2) examine associations between grandmother-mother relationship quality and household investments to promote child development, (3a) qualitatively explore grandmother and mother views on caregiving roles, family dynamics, and grandmother inclusion in SECD-promoting interventions, and (3b) synthesize research findings and use implementation science principles to provide new insights on grandmother inclusion in psychosocial, SECD-promoting interventions. The Bachpan Cohort, a longitudinal birth cohort in rural Pakistan, serves as the parent study. Separate in-depth interviews of grandmothers and mothers from the Bachpan Cohort will be conducted at child age 7. This mixed methods project will generate new insights on grandmother caregiving, family dynamics, and impacts on child SECD. The research findings...