This study is the first-of-its-kind integration of advanced community-level energy system modeling with on-the-ground public outreach and indoor air quality monitoring in an underserved community in eastern Los Angeles County. This novel integration of data and methods has enabled the holistic, quantitative assessment of indoor and ambient air quality benefits of residential building electrification. Results support prioritizing stove and oven electrification to improve indoor air quality and highlight tradeoffs between indoor and ambient air quality improvements. Participant households do not conform to regionwide averages for appliance types, fuel sources, or cooling behaviors. Energy modeling that informs State planning needs to reflect the diversity of local and household level characteristics to appropriately represent and address equity issues. Electrification strategies must also recognize the logistical challenges and costs of electric service panel upgrades and installation of new 240V circuits in underserved communities. Analysis of account-level hourly gas use within the community reveals that peak gas use throughout the day largely coincides with peak times of electricity use. This suggests that aggressive residential electrification will produce new winter season peaks and may amplify current summer peaks. Residential electrification is expected to substantially improve local air quality in communities that implement it, providing considerable reductions in adverse health impacts and their associated costs. The magnitude of these local benefits exceeds the health impacts from increased grid emissions near fossil-fueled generation by a significant margin. However, benefits and impacts may accrue to different populations. Electrification policies and planning for the retirements of fossil-fueled generation facilities must account for the possibility of creating new air pollution hot spots or exacerbating existing hot spots. Consideration should be given to policies that directly fund upgrades and electrification for homes in these hot spots to provide households with the best possible indoor air quality and reduce air pollutant emissions to the ambient environment.