Introduction/Background Preventable deaths in pregnant women and newborns remain unacceptably high in East Africa. Limited antenatal, delivery and postnatal care-seeking combined with service delivery gaps at government facilities contribute to high mortality. Between 2016-2019, partners from Tanzania, Uganda, and Canada jointly developed, implemented, and evaluated a comprehensive, district-wide maternal, newborn, and child health (MNCH) ‘package’ in Lake Zone, Tanzania. Known locally as ‘Mama na Mtoto’, the scale-up programming involved training and capacity building for district managers, health facility staff and a network of volunteer community health workers selected by their own communities. Objectives To quantitatively assess changes in MNCH health outcomes following the Mama na Mtoto intervention. Design/Methods MNCH household-level care-seeking outcomes were assessed using a pre/post coverage survey adapted from the Demographic Health Survey. Households and women (15-49 years), selected through cluster sampling (cluster unit=hamlet), were surveyed by local, trained research assistants using tablet-based surveys. MNCH service outcomes were assessed at all government health facilities using a comprehensive pre/post cross-sectional audit tool; key measures included staff, equipment, infrastructure, supplies, and medication availability. Descriptive statistics for antenatal care (ANC), health facility delivery (HFD), and postnatal care (PNC)-related indicators were analyzed pre- and post-intervention using R software. Composite health facility ‘Readiness Scores’ were calculated through tallies of relevant itemized facility-based measures for each core MNCH service area across the district. Absolute percentage differences, confidence intervals and design effect are presented where relevant. Results In total, 1,977 households, 2,438 women, and 45 health facilities were surveyed pre-intervention and 1,835 homes, 2,073 women, and 49 health facilities were surveyed post. Care-seeking indicators with statistically significant changes were ANC 4+ (+11%), ANC <12 weeks (+7%), HFD (+17%), and PNC for mothers (+9%); PNC for babies was not significant. Increases in composite MNCH Service Readiness Scores were as follows: ANC +24%, essential newborn care +42%, newborn resuscitation +37%, and labour and delivery +27%. Conclusion The comprehensive MnM package was associated with important improvements in the demand (care-seeking) and service (facility readiness) health outcomes. Attribution is complicated by an uncontrolled health system and lack of district controls; however, the extensive scope, reach, and positive changes are promising and consistent with sustained Ugandan experiences. Best practice documentation is critical to facilitate scale-up and progress acceleration of MNCH programs in Tanzanian and East African settings.