Abstract Introduction: While immigrants initially demonstrate better health relative to those US-born, with longer length of US residency, immigrants tend to experience increased risk of many diseases – including breast cancer (BC) – compared to those US-born. However, immigrants are less likely to access preventive health services like BC screenings. Fortunately, research suggests that improved knowledge of BC screening guidelines can lead to increased guideline adherence. This project aimed to describe BC screening guideline knowledge and adherence among female Ohioans over 40 years old and to identify how these characteristics differed by nativity status. Methods: The Community Initiative Towards Improving Equity and Health Status (CITIES) project was a survey of Ohio residents focused on identifying factors contributing to cancer disparities. Wave 1 occurred in 2017-2018. Participants were asked about their knowledge of BC screening guidelines using the item, “At what age are most women supposed to start having mammograms?” The correct age was 40 years. Participants were also asked about their adherence to BC screening guidelines using the item, “How long ago has it been since you had your last mammogram?” Participants were up to date with screening if their last mammogram was within one year. Nativity status was foreign-born or US-born. Frequencies and percentages were used to describe knowledge of and adherence to BC screening guidelines. To identify how BC screening knowledge and adherence differed by nativity status, chi-square tests assessing differences in the frequencies of these factors for those foreign-born and US-born were used. Results: The study sample included 307 women over age 40: 18.6% were foreign-born, 32.2% were Black, non-Hispanic, and the mean age was 61.3 years (SD=7.1). The percentage of women with correct knowledge of BC screening guidelines was 52.4% (n=161). The percentage of women up to date with guidelines was 75.9% (n=233), of which 13.3% (n=31) were foreign- born. Overall, women with correct knowledge were more likely to be up to date with guidelines than were those with incorrect knowledge (43.0% vs. 32.9%; χ 2 p=0.01). This relationship was also observed among US-born women (47.2% vs. 33.6%; χ 2 p=0.04). However, foreign-born women with correct knowledge were no more likely to be up to date with guidelines than were foreign-born women with incorrect knowledge (24.6% vs. 29.8%; χ 2 p=0.42). Conclusions: Half of female Ohioans over age 40 had correct knowledge of BC screening guidelines and three- quarters were up to date with guidelines. More US-born than foreign-born women had correct knowledge of and were up to date with guidelines. A significant association existed between knowledge of BC screening guidelines and being up to date with guidelines among women overall and US-born women, but not among foreign-born women. Future research should identify strategies to improve knowledge of BC screening guidelines among foreign-born women, which may increase their BC screening uptake. Citation Format: Katarina M. Bischof, Mohamed I. Elsaid, Chloe M. Hery, Ryan D. Baltic, Cecilia R. DeGraffinreid, Chasity M. Washington, Electra D. Paskett. Differences by nativity status in knowledge of and adherence to breast cancer screening guidelines: A Community Initiative Towards Improving Equity and Health Status (CITIES) study [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr A096.