Background: Poor adherence to cardiovascular medications is associated with worse clinical outcomes. Evidence for effective education interventions that address medication adherence for the primary prevention of cardiovascular disease is lacking. The Ready to Reduce Risk (3R) study aims to investigate whether a complex intervention, involving group education plus telephone and text messaging follow-up support, can improve medication adherence and reduce cardiovascular risk., Objective: This protocol paper details the design and rationale for the development of the 3R intervention and the study methods used., Methods: This is an open and pragmatic randomized controlled trial with 12 months of follow-up. We recruited participants from primary care and randomly assigned them at a 1:1 frequency, stratified by sex and age, to either a control group (usual care from a general practitioner) or an intervention group involving 2 facilitated group education sessions with telephone and text messaging follow-up support, with a theoretical underpinning and using recognized behavioral change techniques. The primary outcome was medication adherence to statins. The primary measure was an objective, novel, urine-based biochemical measure of medication adherence. We also used the 8-item Morisky Medication Adherence Scale to assess medication adherence. Secondary outcomes were changes in total cholesterol, blood pressure, high-density lipoprotein, total cholesterol to high-density lipoprotein ratio, body mass index, waist to hip ratio, waist circumference, smoking behavior, physical activity, fruit and vegetable intake, patient activation level, quality of life, health status, health and medication beliefs, and overall cardiovascular disease risk score. We also considered process outcomes relating to acceptability and feasibility of the 3R intervention., Results: We recruited 212 participants between May 2015 and March 2017. The 12-month follow-up data collection clinics were completed in April 2018, and data analysis will commence once all study data have been collected and verified., Conclusions: This study will identify a potentially clinically useful and effective educational intervention for the primary prevention of cardiovascular disease. Medication adherence to statins is being assessed using a novel urine assay as an objective measure, in conjunction with other validated measures., Trial Registration: International Standard Randomized Controlled Trial Number ISRCTN16863160; http://www.isrctn.com/ISRCTN16863160 (Archived by WebCite at http://www.webcitation.org/734PqfdQw)., International Registered Report Identifier (irrid): DERR1-10.2196/11289., (©Jo L Byrne, Helen M Dallosso, Stephen Rogers, Laura J Gray, Ghazala Waheed, Prashanth Patel, Pankaj Gupta, Yvonne Doherty, Melanie Davies, Kamlesh Khunti. Originally published in JMIR Research Protocols (http://www.researchprotocols.org), 12.11.2018.)