Cervical cancer (CC) is the second leading cause of cancer death among women in Mexico, yet screening participation is alarmingly low, with less than 30% of women aged 20 or older having ever been screened in 2022. Human papillomavirus (HPV) self-sampling is an effective method that increases accessibility for women facing barriers such as embarrassment, fear of pain, or logistical challenges. The Mexican Social Security Institute (IMSS), the largest healthcare provider in Mexico, serves 31 million women and has begun to implement programs to examine the potential of using HPV-based screening. In October 2022, IMSS launched the IMSS Maquiladora HPV Screening Program (IMHSP) in Chihuahua, targeting 35,000 under-screened women working in maquiladoras. As of April 2024, 11,878 workers were screened, but adoption, implementation, and effectiveness varied widely across maquiladoras and there was sub-optimal follow-up to abnormal results. Our long-term goal is to reduce CC morbidity and mortality in Mexico. The goal of the proposed study is to identify factors influencing the adoption, implementation, and sustainment of the IMHSP, assess program effectiveness and implementation outcomes, and design implementation strategies to improve program use and sustainment. Using Implementation Mapping, the Consolidated Framework for Implementation Research (CFIR), and RE-AIM, we will: 1) Identify barriers and facilitators to the adoption and implementation of the IMHSP and describe implementation and effectiveness outcomes by conducting interviews, observations, and discussion sessions with stakeholders and personnel in maquiladoras and IMSS clinics. 2) Explore factors influencing program integration and screening completion from the perspectives of patients and IMSS healthcare providers in clinical settings. We will conduct semi-structured interviews with female workers who participated in the program and were HPV positive, and with clinical personnel at IMSS clinics; and, 3) Design implementation strategies based on findings. This proposal if for an administrative supplement to a parent U54 LISTOS (Leveraging Implementation Science to Optimize Strategies) for cancer control. LISTOS is a National Cancer Institute (NCI)-funded center through the Global Implementation Science for Equitable Cancer Control (GlobalISE Cancer Control) program to establish implementation science centers in low- and middle-income countries (LMICs). The LISTOS center focuses on strengthening implementation research and research capacity in Mexico and Latin America. This proposed study advances the goals of LISTOS and provides training opportunities for our junior colleagues. This study addresses a pressing need for improved cervical cancer control in Mexico and will inform scalable strategies to enhance screening participation across worksites significantly advancing public health efforts and reducing cervical cancer mortality in underserved populations.