PROPOSAL SUMMARY/ABSTRACT The US opioid crisis has had a significant effect on many populations, not the least of which effected are perinatal women. The prevalence of opioid use disorder (OUD) among women giving birth in hospitals increased by 131% from 2010-2017. OUD in pregnancy and postpartum increases the risks for a host of medical complications and can lead to adverse birth outcomes including preterm delivery and intrauterine fetal demise, as well as maternal morbidity and mortality. Loneliness and social isolation are also linked to poorer progression of acute, chronic, physical, and mental conditions, as well as mortality, and are compounded during the perinatal period (which is defined as pregnancy and the first postpartum year). Both loneliness and social isolation have been linked to increased opioid use amount, relapse rates, and overdose even when controlling for OUD treatment, employment, relationship status, and depression. To address both loneliness and engagement in perinatal and OUD care among perinatal women, we plan to adapt an existing texting support chatbot, Penny, to make it appropriate for use by women who are pregnant and postpartum and dealing with OUD. The newly adapted chatbot, Penny COPILOT, will allow for two way short message service (SMS) messaging using natural language processing to respond appropriately and accurately to user generated input. In this way, Penny COPILOT feels like texting a friend, as it responds using real sentences and minimizes awkward confirmatory messages. Our team, in collaboration with the Penn Mixed Methods Research Lab (MMRL) and Memora Health Technology Company, will use intervention mapping guided by the Consolidated Framework for Implementation Science. We will conduct a needs assessment, assemble an advisory board, engage in pretesting to ensure safety and refine content, and pilot test the resultant adapted Penny COPILOT in a sample of 20 perinatal women with OUD to evaluate acceptability, feasibility, and patient satisfaction. Our goal is to develop and refine an acceptable, feasible, and satisfactory supportive texting chatbot to promote patient engagement in perinatal and OUD care and decrease perceived loneliness.