Background: Persistent smoking after cancer diagnosis causes adverse clinical outcomes. ASCO and other organizations view smoking assessment and treatment as indicators of high-quality cancer care. Yet, adoption of clinical practice guidelines like the 3As (Ask, Advise and Assist) for smoking assessment and treatment has been slow and inconsistent in cancer care settings. Methods: Led by the American College of Surgeons Cancer Programs’ Commission on Cancer (CoC) and National Accreditation Program for Breast Centers (NAPBC), the “Just ASK” national quality improvement project focuses on enhancing smoking assessment and treatment in cancer care settings. All CoC/NAPBC programs (n~2000) were invited to participate, which consisted of educational webinars, online resources, and 3 online surveys (baseline, 6- and 12-month) collecting information on smoking assessment and treatment practices, plus other variables (e.g., organizational priority, implementation barriers). Program participation was incentivized by fulfillment of accreditation standards. Results: In total, 776 programs (731 CoC, 45 NAPBC), participated. At baseline, most programs strongly endorsed the importance of addressing smoking within cancer care and the majority of programs reported routinely assessing smoking (90%) and advising all patients reporting current smoking to quit (71%). However, routine delivery of evidence-based smoking cessation assistance (e.g., quitline referral, cessation medications, counseling services) was low (all < 30%). Program retention was excellent (91%). As shown in the table, the 12-month follow-up revealed marked improvements in evidence-based Ask, Advise and Assist, practices. Conclusions: At enrollment, the importance of addressing smoking was evident and high rates of smoking assessment were reported. At 12-month follow-up, marked improvement was reported in all quality indicators of the 3As. These findings guided the sharing of strategies for improving patient assessment, clinical workflow and documentation. Suboptimal delivery of smoking cessation assistance persisted despite overall improvements, which highlight persistent challenges and opportunities for implementing smoking assessment and treatment in cancer care settings.