The LISTOS Research Capacity Building Core (RCBC) will accomplish the following aims: (1) develop a two-tiered training and mentoring program to build implementation research capacity for cancer control in Mexico and Latin America; (2) establish three implementation science (IS) capacity-building units (training & resources, implementation strategies, and methods & measurement) to coordinate and support the training and mentoring program; and (3) create an implementation research pilot program for cancer control in Mexico and Latin America. In accomplishing these aims, the RCBC will address key gaps that have plagued capacity building efforts for cancer control implementation research in LMIC settings. This core will target gaps in capacity building through enhanced mentoring, coaching, and technical assistance; provide novel and innovative methods of developing the capacity of investigators in Mexico and Latin America specific to their needs; conduct trainings and develop tools in Spanish to overcome language barriers; and establish a pilot program to expand the impact of RCBC efforts. The three functional units of the RCBC will include investigators from all partner institutions, fostering a collaborative environment that allows for two-way dialogue between local practitioners and healthcare organization partners in Mexico and Latina American, and between Mexican (INSP, INCan) and US-based IS partners (UTHealth, UCSF). Innovative capacity building strategies will be supported through the RCBC, including establishing Project ECHO programs in Mexico and supporting participation by local investigators in D&I certificate programs. Key outputs of RCBC activities will include the adaptation of and training LISTOS partners on key implementation research tools. Implementation research tools and training will be made available to investigators in LISTOS networks in Mexico and Latin America, as well as to members of the U54 Global Cancer Consortium. RCBC efforts will build the capacity of a cadre of outstanding young investigators from Mexico and Latin America to conduct cancer IS research and address cancer related health inequities in Latin America.