The Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial is a randomized, multicenter clinical trial using a double 2 x 2 factorial design in 10,251 participants with type 2 diabetes mellitus at high risk for cardiovascular disease (CVD) events. ACCORD is testing 3 complementary medical treatment strategies that may reduce high rates of major CVD morbidity and mortality in patients with type 2 diabetes. The ACCORD vanguard phase, conducted at 59 clinics in the United States and Canada, recruited 1,174 participants in 20 weeks from January through June 1, 2001, with a recruitment efficiency (R-factor) of 0.65. The recruitment strategies used in this vanguard phase were almost exclusively chart and database review within clinical practices and institutions. Recruitment for the main trial began in February 2003, involved 77 clinics, and resulted in an additional 9,077 participants by October 29, 2005 (total, 10,251). The R-factor during main trial recruitment was 0.96. Although new and refined recruitment strategies were formulated from the vanguard experience, the most powerful determinant of improved recruitment efficiency was the immediate start of enrollment by most clinics at the beginning of the main trial. Recruitment in the main trial required only a brief extension of 3 months and facilitated the nearly complete capture of the expected number of person-years of observation. Described herein are vanguard and main trial recruitment activities, including strategy implementation, screening procedures, randomization results, problems encountered, and lessons learned.