Background Puerto Ricans, the second largest US Latino group, are underrepresented in genomic studies of Alzheimer disease (AD). We describe a multi‐source ascertainment approach, networking with community and governmental stakeholders, as part of the Puerto Rico (PR) Alzheimer Disease Initiative (PRADI) whose goal is to increase recruitment and retention of PR individuals in genomic research.The National Alzheimer’s disease Action Plan 2015‐2025 served as a framework for PRADI group that aims to fill two of the goals of the plan: increase research and education. Method We developed collaborative relationships with community and governmental organizations that serve the elderly and AD patients from 37/78 (47%) municipalities of PR to identify potential research participants. Trust and transparency were central to our interactions with community groups. We educated patients and caregivers about AD and their possible contribution to science. Bringing academia to the community encouraged participation. Additionally, we established relationships with multiple neurologists across PR caring for AD patients and their families. For recruitment and enrollment PRADI team members visited families in the homes, daycare facilities and clinics. All participants were assigned diagnoses by a clinical adjudication committee comprised of neurologists and neuropsychologists with expertise in AD and related dementias (ADRD) Result Since 2016 we have enrolled 1, 281 individuals. Among these 752 are unrelated individuals (193 AD, 170 mild cognitive impairment (MCI), 306 cognitively unimpaired (CU) and 83 with other diagnoses (OD). 529 individuals (195 AD, 76 MCI, 178 CU and 80 OD) were part of 155 multiplex AD families. Most families are from Eastern and Northern PR regions, reflecting dense population areas with large cities. Longitudinal follow‐up of the first 167 participants for diagnostic updates is complete. 64 individuals were ascertained in the continental US (cUS). Of the 167 individuals in the longitudinal follow‐up (3‐5 years), 7.2% progressed from either CU to MCI or AD, or MCI to AD. Conclusion The PRADI group multisource ascertainment approach enabled recruitment and retention of participants both in PR and the cUS. Longitudinal clinical data across the cohort further enriches the impact of genomic studies in a diverse population.