Background Population-wide reduction in mean blood pressure is proposed as a key strategy for primary prevention of cardiovascular disease. We evaluated the effectiveness of a task-sharing strategy involving frontline health workers in the primary prevention of elevated blood pressure. Methods and Results We conducted DISHA (Diet and lifestyle Interventions for Hypertension Risk reduction through Anganwadi Workers and Accredited Social Health Activists) study, a cluster randomized controlled trial involving 12 villages each from 4 states in India. Frontline health workers delivered a custom-made and structured lifestyle modification intervention in the selected villages. A baseline survey was conducted in 23 and 24 clusters in the control (n=6663) and intervention (n=7150) groups, respectively. The baseline characteristics were similar between control and intervention clusters. In total 5616 participants from 23 clusters in the control area and 5699 participants from 24 clusters in the intervention area participated in a repeat cross-sectional survey conducted immediately after the intervention phase of 18-months. The mean (SD) systolic blood pressure increased from 125.7 (18.1) mm Hg to 126.1 (16.8) mm Hg in the control clusters, and it increased from 124.4 (17.8) mm Hg to 126.7 (17.5) mm Hg in the intervention clusters. The population average adjusted mean difference in difference in systolic blood pressure was 1.75 mm Hg (95% CI, -0.21 to 3.70). Conclusions Task-sharing interventions involving minimally trained nonphysician health workers are not effective in reducing population average blood pressure in India. Expanding the scope of task sharing and intensive training of health workers such as nurses, nutritionists, or health counselors in management of cardiovascular risk at the population level may be more effective in primary prevention of cardiovascular disease. Registration URL: https://www.ctri.nic.in; Unique identifier: CTRI/2013/10/004049.