This is the final version of the article. Available from NIHR Health Technology Assessment Programme via the DOI in this record. ; Background Shortfalls in the receipt of recommended health care have been previously reported in England, leading to preventable poor health. Objectives To assess changes over 6 years in the receipt of effective health-care interventions for people aged 50 years or over in England with cardiovascular disease, depression, diabetes or osteoarthritis; to identify how quality varied with participant characteristics; and to compare the distribution of illness burden in the population with the distributions of diagnosis and treatment. Setting and participants Information on health-care quality indicators and participant characteristics was collected using face-to-face structured interviews and nurse visits in participants’ homes by the English Longitudinal Study of Ageing in 2004–5, 2006–7, 2008–9 and 2010–11. A total of 16,773 participants aged 50 years or older were interviewed at least once and 5114 were interviewed in all four waves; 5404 reported diagnosis of one or more of four conditions in 2010–11. Main outcome measures Percentage of indicated health care received by eligible participants for 19 quality indicators: seven for cardiovascular disease, three for depression, five for diabetes and four for osteoarthritis, and condition-level quality indicator achievement, including achievement of a bundle of three diabetes indicators. Analysis Changes in quality indicator achievement over time and variations in quality with participant characteristics were tested with Pearson’s chi-squared test and logistic regression models. The size of inequality between the hypothetically wealthiest and poorest participants, for illness burden, diagnosis and treatment, was estimated using slope indices of wealth inequality. Results Achievement of indicators for cardiovascular disease was 82.7% [95% confidence interval (CI) 79.9% to 85.5%] in 2004–5 and 84.2% (95% CI 82.1% to 86.2%) in 2010–11, for depression 63.3% (95% CI 57.6% to 69.0%) and 59.8% (95% CI 52.4% to 64.3%), for diabetes 76.0% (95% CI 74.1% to 77.8%) and 76.5% (95% CI 74.8% to 78.1%), and for osteoarthritis 31.2% (95% CI 28.5% to 33.8%) and 35.6% (95% CI 34.2% to 37.1%). Achievement of the diabetes care bundle was 67.8% (95% CI 64.5% to 70.9%) in 2010–11. Variations in quality by participant characteristics were generally small. Diabetes indicator achievement was worse in participants with cognitive impairment [odds ratio (OR) 0.5, 95% CI 0.4 to 0.7] and better in those living alone (OR 1.7, 95% CI 1.3 to 2.0). Hypertension care was better for those aged over 74 years (vs. 50–64 years) (OR 3.2, 95% CI 2.0 to 5.3). Osteoarthritis care was better for those with severe (vs. mild) pain (OR 1.8, 95% CI 1.4 to 2.2), limiting illness (OR 1.8, 95% CI 1.5 to 2.1), and obesity (OR 1.6, 95% CI 1.2 to 2.0). Previous non-achievement of the diabetes care bundle was the biggest predictor of non-achievement 2 years later (OR 3.3, 95% CI 2.2 to 4.7). Poorer participants were always more likely than wealthier participants to have illness burden (statistically significant OR 3.9 to 16.0), but not always more likely to be diagnosed or receive treatment (0.2 to 5.3). Conclusions Shortfalls in quality of care for these four conditions have persisted over 6 years, with only half of the level of indicated health care achieved for osteoarthritis, compared with the other three conditions. Quality for osteoarthritis improved slightly over time but remains poor. The relatively high prevalence of specific illness burden in poorer participants was not matched by an equally high prevalence of diagnosis or treatment, suggesting that barriers to equity may exist at the stage at diagnosis. Further research is needed into the association between quality and health system characteristics at the level of clinicians, general practices or hospitals, and regions. Linkage to routinely collected data could provide information on health service characteristics at the individual patient level. ; Funding for this study was provided by the Health Services and Delivery Research programme of the National Institute for Health Research.