Abstract Background: Engaging regularly in physical activity (PA) can lower cancer risks. Existing literature shows that South Asian women and girls residing in the U.S. have low moderate-to-vigorous PA (MVPA); however, there is little research on the influence of unique sociocultural determinants such as acculturation on PA. Even less is known about the association between acculturation and PA in South Asian mother-daughter dyads, especially where the two have different acculturation levels. Methods: Data came from the baseline assessment of the South Asians Active Together (SAATH) trial, a two-arm randomized clinical trial of an 8-week culturally adapted intervention to increase PA among South Asian mothers and daughters. Mainstream U.S. acculturation and Asian acculturation were measured for each separately using the Suinn-Lew Asian Self Identity Acculturation Scale (SL-ASIA; range 1-5, higher scores indicate higher acculturation). (Mainstream U.S. acculturation corresponds to the “Western” acculturation construct in SL-ASIA; here we refer to that same concept using a more nuanced term that better reflects the complexities of acculturation for immigrants in the U.S.) PA variables include PA barriers, PA self-efficacy, self-reported transportation and leisure-time MVPA, and accelerometer-measured MVPA (minutes/day). Using the Actor Partner Interdependence Model (APIM) in R (version 4.4) and controlling for age as a covariate, we tested dyadic associations between mothers’ and daughters’ mainstream U.S. and Asian acculturation and PA variables. Results: The baseline assessment included 126 mother-daughter dyads. On average, participants’ Asian acculturation score (M=4.5, SD=0.6 for mothers; M=3.9, SD=0.8 for daughters) was higher than U.S. acculturation score (M=3.1, SD=1.0 for mothers; M=3.4, SD=0.8 for daughters). In APIM analyses, for daughters, higher U.S. acculturation was associated with lower PA barriers (β=-0.20), and higher Asian acculturation was associated with higher PA self-efficacy (β=0.18). For mothers, higher U.S. acculturation was associated with lower PA barriers (β=-0.20) and higher PA self-efficacy (β=0.21). For mothers, higher Asian acculturation was also associated with lower PA barriers (β=-0.23), higher PA self-efficacy (β=0.36), and higher accelerometer-measured MVPA (β=26.71). Interestingly, mothers’ Asian acculturation was also positively associated with daughters’ PA self-efficacy (β=0.16). Conclusion: We observed positive associations of both U.S. and Asian acculturation with several PA-related variables among South Asian mothers and daughters, which underscores the importance of bilinear acculturation measurements and influences on PA. Mothers’ Asian acculturation was associated with daughters’ PA self-efficacy, which merits further exploration. Citation Format: Milkie Vu, Soyang Kwon, Nicola Lancki, Rency Roy, Mudita Rastogi, David Marquez, Namratha Kandula. Physical activity among South Asian mother-daughter dyads residing in the U.S.: Influence of U.S. and Asian acculturation [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 B072.