Background The World Health Organization (WHO) has reframed health and healthcare for older people around achieving the goal of healthy ageing. The recent WHO Integrated Care for Older People (ICOPE) guidelines focus on maintaining intrinsic capacity, i.e., addressing declines in neuromusculoskeletal, vitality, sensory, cognitive, psychological, and continence domains, aiming to prevent or delay the onset of dependence. The target group with 1 or more declines in intrinsic capacity (DICs) is broad, and implementation may be challenging in less-resourced settings. We aimed to inform planning by assessing intrinsic capacity prevalence, by characterising the target group, and by validating the general approach—testing hypotheses that DIC was consistently associated with higher risks of incident dependence and death. Methods and findings We conducted population-based cohort studies (baseline, 2003–2007) in urban sites in Cuba, Dominican Republic, Puerto Rico, and Venezuela, and rural and urban sites in Peru, Mexico, India, and China. Door-knocking identified eligible participants, aged 65 years and over and normally resident in each geographically defined catchment area. Sociodemographic, behaviour and lifestyle, health, and healthcare utilisation and cost questionnaires, and physical assessments were administered to all participants, with incident dependence and mortality ascertained 3 to 5 years later (2008–2010). In 12 sites in 8 countries, 17,031 participants were surveyed at baseline. Overall mean age was 74.2 years, range of means by site 71.3–76.3 years; 62.4% were female, range 53.4%–67.3%. At baseline, only 30% retained full capacity across all domains. The proportion retaining capacity fell sharply with increasing age, and declines affecting multiple domains were more common. Poverty, morbidity (particularly dementia, depression, and stroke), and disability were concentrated among those with DIC, although only 10% were frail, and a further 9% had needs for care. Hypertension and lifestyle risk factors for chronic disease, and healthcare utilisation and costs, were more evenly distributed in the population. In total, 15,901 participants were included in the mortality cohort (2,602 deaths/53,911 person-years of follow-up), and 12,939 participants in the dependence cohort (1,896 incident cases/38,320 person-years). One or more DICs strongly and independently predicted incident dependence (pooled adjusted subhazard ratio 1.91, 95% CI 1.69–2.17) and death (pooled adjusted hazard ratio 1.66, 95% CI 1.49–1.85). Relative risks were higher for those who were frail, but were also substantially elevated for the much larger sub-groups yet to become frail. Mortality was mainly concentrated in the frail and dependent sub-groups. The main limitations were potential for DIC exposure misclassification and attrition bias. Conclusions In this study we observed a high prevalence of DICs, particularly in older age groups. Those affected had substantially increased risks of dependence and death. Most needs for care arose in those with DIC yet to become frail. Our findings provide some support for the strategy of optimising intrinsic capacity in pursuit of healthy ageing. Implementation at scale requires community-based screening and assessment, and a stepped-care intervention approach, with redefined roles for community healthcare workers and efforts to engage, train, and support them in these tasks. ICOPE might be usefully integrated into community programmes for detecting and case managing chronic diseases including hypertension and diabetes., In a population-based cohort study, Martin J. Prince and colleagues evaluate intrinsic capacity and its associations with incident dependence and mortality in Latin America, India and China., Author summary Why was this study done? As we grow older, we are affected to different degrees by declines in the working of our organs and body systems, limiting our ability to get around, be well nourished, see, hear, and think clearly, stay continent, and maintain mood and well-being. The World Health Organization has proposed a programme—Integrated Care for Older People (ICOPE)—supported by evidence that simple interventions may slow or reverse these processes, with potential to improve health and functioning and delay needs for care developing among older people. ICOPE targets low- and middle-income countries, but we do not yet know how many older people in these settings are significantly affected by early age-related decline, or whether these changes predict who will go on to deteriorate further, leading to needs for care and earlier death. What did the researchers do and find? We had already completed (between 2003 and 2007) baseline community surveys of 17,031 people aged 65 years and over living in 12 urban and rural sites in 6 Latin American countries, India, and China; we then tried to interview them again 3 to 5 years later (between 2008 and 2010) to identify who had died (in 11 sites, among 15,901 older people) and who had developed needs for care (in 10 sites, among 12,939 older people). Analysing baseline data from these studies, we found that between two-thirds and three-quarters of older people were affected by significant decline in at least 1 of the areas targeted by the ICOPE programme; this proportion was highest among the older old, who were also more likely to have problems in multiple areas. Most (nearly three-quarters) of those with significant decline at baseline had not yet gone on to become physically frail or develop needs for care; they were nevertheless 1.7 to 1.9 times more likely than those without any significant decline to develop needs for care over the follow-up period, and 1.3 to 1.4 times more likely to have died. What do these findings mean? Delivering comprehensive assessment, care planning, and community interventions to up to three-quarters of the older population would be a major challenge for poorly resourced health systems in low- and middle-income countries. Nevertheless, findings from our analyses support the World Health Organization’s strategy to promote health and well-being by targeting a broad group with early decline who do seem to be at increased risk of adverse outcomes. Future research should focus upon feasible, acceptable, and efficient methods of delivering the ICOPE programme (implementation science) and its effectiveness and cost-effectiveness in improving health and social outcomes (controlled trials). The main limitations were that health declines were measured in different ways, some of which may have been imprecise, and those who could not be followed up may have had different characteristics to those who were included in the analysis.