Objective: To determine whether an advance directive redesigned to meet most adults' literacy needs (fifth grade reading level with graphics) was more useful for advance care planning than a standard form (>12th grade level). Methods: We enrolled 205 English and Spanish-speaking patients, aged ≥50 years from an urban, general medicine clinic. We randomized participants to review either form. Main outcomes included acceptability and usefulness in advance care planning. Participants then reviewed the alternate form; we assessed form preference and six-month completion rates. Results: Forty percent of enrolled participants had limited literacy. Compared to the standard form, the redesigned form was rated higher for acceptability and usefulness in care planning, P ≤ 0.03, particularly for limited literacy participants (P for interaction ≤0.07). The redesigned form was preferred by 73% of participants. More participants randomized to the redesigned form completed an advance directive at six months (19% vs. 8%, P = 0.03); of these, 95% completed the redesigned form. Conclusions: The redesigned advance directive was rated more acceptable and useful for advance care planning and was preferred over a standard form. It also resulted in higher six-month completion rates. Practice implications: An advance directive redesigned to meet most adults' literacy needs may better enable patients to engage in advance care planning. © 2007 Elsevier Ireland Ltd. All rights reserved.