Abstract Body (Do not enter title and authors here): Introduction: Emerging evidence shows increased cardiovascular disease (CVD) risk in Black women of childbearing age (18-49 years), a critical window for CVD prevention. Racial discrimination has been linked by various physiological pathways to CVD risks. Using ecological momentary assessment (EMA), this study aimed to examine daily experiences of microaggressions and discrimination among Black women and their potential impact on vascular function. Research Questions: (1) How often do Black women experience microaggressions and discrimination in their daily lives? (2) Are daily experiences of discrimination and microaggressions associated with vascular function? Methods: Black women of childbearing age without hypertension (N=27) underwent a lab-based peripheral vascular function assessment using flow-mediated dilation (FMD) of the brachial artery. They also answered 4 daily EMA surveys at random intervals over a 10-day monitoring period on their smartphones. Surveys included questions from validated measures assessing the experience of microaggression and discrimination. Logistic regression was used to explore associations between FMD and experiences of microaggression and discrimination, accounting for age and perceived stress. Results: On average, study participants reported 14 incidents of microaggression (SD=18.7, range=0-73) and 4 discriminatory events (SD=5.0, range=0-21) over the 10-day monitoring period. More than half (54%) reported more than 5 microaggression incidents, and 64% reported at least 1 discriminatory event. Half (50%) were at a higher risk for CVD (FMD<6%; M= 6.3, SD=2.7, range=1.7-12.9). Higher risk for CVD was associated with experiencing fewer microaggression incidents (≤5 vs. >5 incidents; B=-1.84, p=.048) and marginally associated with experiencing no discriminatory events (0 vs. at least 1 event; B=-2.74, p=.058). Conclusions: On average, Black women of childbearing age report experiencing microaggressions daily and discriminatory events about every two days. EMA can be a feasible tool to assess these daily experiences among Black women, and these daily experiences can vary across individuals. While more frequent experiences of microaggressions and discrimination were not associated with higher CVD risks in this preliminary sample, future studies can further investigate the potential protective (e.g., coping skills, social support) and risk factors (e.g., stress, unhealthy behaviors) related to daily experiences and CVD risks.