Abstract The Gateway to Global Aging Data (g2aging.org) is a data and information platform developed to facilitate longitudinal and cross-country analyses on aging, especially those using the family of Health and Retirement Studies (HRS) around the world. The Gateway has indexed metadata from 18 surveys in 46 countries and has created 27,449 key harmonized variables on demographics, health, financial and housing wealth, income, family structure, retirement, employment history, cognition, consumption, health care, and pension for cross-wave/cross-country analysis. Most recently, we incorporated newly available Harmonized Cognitive Assessment Protocol (HCAP) data from three countries, the HRS-HCAP in the United States, the Mexican Health and Aging Study’s MEX-COG, and the Longitudinal Aging Study in India’s LASI-DAD, offering the opportunity to further study Alzheimer’s disease and Alzheimer’s disease-related dementias (AD/ADRD) in these three countries. Since then, the English Longitudinal Study of Ageing (ELSA) released its HCAP data, ELSA-HCAP, to the public, and the Chilean version of HCAP, Chile-COG was collected in August-December 2019 and will be available for public release later this year. In this application, we aim to incorporate the ELSA-HCAP and Chile-COG into the Gateway to Global Aging Data. As with the Harmonized HRS-HCAP, MEX-COG, and LASI-DAD, we will identify common cognitive tests and informant reports, construct harmonized measures, and disseminate the comparable data files to the wider user community, facilitating research on late-life cognition, AD/ADRD in two new countries, England and Chile. By doing so, we will save individual researchers’ time and effort in constructing such measures and eliminate potential errors in analysis data construction, improving the replicability of findings and accelerating scientific advances in cognition, AD/ADRD related topics. Furthermore, we aim to build a user community and encourage comparative studies of late-life cognition and AD/ADRD, by organizing webinars and supporting in-person workshops to facilitate the use of the Harmonized HCAP data. The proposed addition of newly available HCAP data and user training will facilitate interested researchers to exploit newly available data to better understand the causes and consequences of cognitive decline and AD/ADRD.