Abstract This project will develop and test a scale-up focused implementation approach for addressing pregnancy-related and -associated morbidity and mortality (PRAMM) and disparities. Previous efforts have shown that use of hospital- focused maternal safety bundles are an important part of successful efforts to reduce PRAMM. However, overall quality of obstetric care improved in these efforts without any effect on disparities. Thus, unlike previous efforts, the proposed project will implement quality improvement bundles that: (1) focus on PRAMM disparities; and (2) focus on community care (i.e., care provided outside the hospital in outpatient and other community settings) and coordination among care settings. Given that 83% of U.S. pregnancy-related and pregnancy-associated deaths occur during pregnancy or postpartum (rather than around the time of delivery), outpatient and community efforts are vital. Bundles (the evidence-based practices to be implemented) are developed by the national Alliance for Innovation on Maternal Health Community Care Initiative (AIM-CCI) and include “Community care for postpartum safety and wellness,” and “Community care for maternal mental health,” “Chronic conditions,” and “Intimate partner violence” bundles. All bundles target PRAMM disparities. 1. Aim 1 of the proposed project will analyze bundle implementation experiences in 2 counties to develop a county-wide scale-up focused implementation approach for the bundles in partnership with stakeholders date to create and manualize a scale-up implementation intervention. 2. Aim 2 will evaluate the effectiveness and cost-effectiveness of the scale-up implementation intervention using a stepped wedge design in 12 Michigan counties with a total population of nearly 6 million people. PRAMM outcomes (individual level) will be extracted from a pre-existing statewide linked dataset. The sample for these analyses will include all Medicaid insured individuals in the 12 counties observed during pregnancy, at birth, and up to 1 year postpartum during the project period (~151,920 births). Implementation outcomes (provider-level) include scale-up (penetration, reach, control for delivery, and intervention effectiveness at scale) and sustainment (maintenance of fidelity to core elements, health benefits, and capacity to deliver core elements over time). This project is innovative because it: (1) is the first controlled implementation trial to test approaches to implementing quality improvement bundles that: (a) specifically target PRAMM disparities; and (b) focus on community care; (2) advances the science of scale-up (it is the first study of which we are aware to test scale- up or sustainment implementation approaches to addressing maternal morbidity/mortality disparities); and (3) works to improve services across many (vs. a single) health systems. The project is significant because we need to reach pregnant women at scale, and scale-up is an understudied aspect of implementati...