Large-scale hypertension screening campaigns have been recommended for middle-income countries. We sought to identify sociodemographic predictors of hypertension prevalence, diagnosis, treatment, and control among middle-income countries. We analyzed data from 47 443 adults in all 6 middle-income countries (China, Ghana, India, Mexico, Russia, and South Africa) sampled in nationally representative household assessments from 2007 to 2010 as part of the World Health Organization Study on Global Aging and Adult Health. We estimated regression models accounting for age, sex, urban/rural location, nutrition, and obesity, as well as hypothesized covariates of healthcare access, such as income and insurance. Hypertension prevalence varied from 23% (India) to 52% (Russia), with between 30% (Russia) and 83% (Ghana) of hypertensives undiagnosed before the survey and between 35% (Russia) and 87% (Ghana) untreated. Although the risk of hypertension significantly increased with age (odds ratio, 4.6; 95% confidence interval, 3.0–7.1; among aged, 60–79 versus <40 years), the risk of being undiagnosed or untreated fell significantly with age. Obesity was a significant correlate to hypertension (odds ratio, 3.7; 95% confidence interval, 2.1–6.8 for obese versus normal weight), and was prevalent even among the lowest income quintile (13% obesity). Insurance status and income also emerged as significant correlates to diagnosis and treatment probability, respectively. More than 90% of hypertension cases were uncontrolled, with men having 3 times the odds as women of being uncontrolled. Overall, the social epidemiology of hypertension in middle-income countries seems to be correlated to increasing obesity prevalence, and hypertension control rates are particularly low for adult men across distinct cultures.