The Division of Cancer Prevention (DCP) at the National Cancer Institute (NCI) announces this Notice of Special Interest to encourage current grant or cooperative agreement awardees to apply for administrative supplement funds to support the development of tools and strategies to increase the participation of individuals from all population subgroups who are representative of people for whom the parent grant  intervention may be indicated. DCP led or co-led programs appropriate for this opportunity include Cancer Prevention and Control Clinical Trials Grant Program, Cancer Prevention Clinical Trials Network (CP-CTNet), NCI Community Oncology Research Program (NCORP) Research Bases, NCORP Community Sites and NCORP Minority/Underserved Community Sites, Prevention of HPV-related Cancers in HIV-infected individuals: United States-Latin American-Caribbean Clinical Trials Network: Partnership Centers Program and the NCI Cancer Screening Research Network: ACCrual, Enrollment, and Screening Sites (ACCESS) Hub. The proposed strategies and tools should be designed to promote inclusion of historically underserved populations in clinical trials - by identifying and reducing enrollment barriers at the organizational, participant, or protocol design level.