13 Background: Cancer incidence is rising in adolescents and young adults (AYA) (age 18-39), a population that faces durable financial challenges during and after treatment. Although AYA cancer survivors face unique risks for poor outcomes due to financial toxicity (FT), best practices for FT and social needs screening (i.e. food, housing, transportation insecurity) are unknown. Further, the relationship between FT and social needs is largely unexplored in AYA. Methods: A FT and social needs screening quality improvement project was conducted at a comprehensive cancer center. The Comprehensive Score for Financial Toxicity (COST) assessed FT, and patients reported unmet social needs and treatment payment methods. Quality of life (QOL) was assessed via a visual analog scale. Multivariate linear and logistic regression tested for associations with FT and unmet social needs, adjusting for demographic and clinical characteristics. Results: Of 70,983 requests, 38,249 patients completed the screening (54% response rate): 2,519 were AYA. Mean age of AYA was 33.7 years (SD 4.7), and most (65%) were non-Hispanic white. Disease sites included 41% breast, 20% gastrointestinal, and 19% gynecologic. Over one-half (54%) had active cancer treatment (chemotherapy, radiation, or surgery) within 120 days of assessment. Mean COST was 23.2 (SD 10.8; 0-44, with lower scores indicating worse FT), and 54% had COST <26, suggesting FT. Racial/ethnic minority patients (β -4.37, p<0.001) and those who had recent treatment (β -3.21, p<0.001) had worse FT. Of those who screened positive for FT, only 44% accepted a referral for financial assistance. About one-quarter of the sample (28%) were unable to afford at least one social need, with 16% facing housing, 14% transportation, and 13% food insecurity. Patients who are a racial/ethnic minority (OR 2.98, 95% CI 2.35-3.79, p<0.001) and those with metastatic disease (OR 2.45, 95% CI 1.10-5.45, p=0.028) were more likely to have at least one unmet social need. One-quarter of the sample (24%) used at least some of their savings to pay for treatment, with 7% reporting they did not have any savings. 25% borrowed money or took on new loans to pay for treatment: of those, 58% borrowed from friends/family. 10% did not have enough money for medications, and 7% took less medications than prescribed due to cost. Mean QOL was 7.3 [(SD 1.8) 0 “as bad as it can be”-10 “as good as it can be”]. Increased FT was associated with reduced QOL (β -0.10, p<0.001), using more savings to pay for treatment (β 0.52, p<0.001), and taking less medications due to cost (β 0.01, p<0.001). Conclusions: Routine FT and social needs screening is feasible for AYA patients and uncovers high rates of FT and unmet social needs. Given lower QOL and decreased adherence to treatment associated with FT, future research should focus on interventions to support the specific needs of AYA and increase acceptance of financial assistance and navigation.