BACKGROUND: Little is known about patient characteristics associated with comprehension of consent information, and whether modifications to the consent process can promote understanding. OBJECTIVE: To describe a modified research consent process, and determine whether literacy and demographic characteristics are associated with understanding consent information. DESIGN: Descriptive study of a modified consent process: consent form (written at a sixth-grade level) read to participants, combined with 7 comprehension questions and targeted education, repeated until comprehension achieved (teach-to-goal). PARTICIPANTS: Two hundred and four ethnically diverse subjects, aged ≥ 50, consenting for a trial to improve the forms used for advance directives. MEASUREMENTS: Number of passes through the consent process required to achieve complete comprehension. Literacy assessed in English and Spanish with the Short Form Test of Functional Health Literacy in Adults (scores 0 to 36). RESULTS: Participants had a mean age of 61 years and 40% had limited literacy (s-TOHFLA<23). Only 28% of subjects answered all comprehension questions correctly on the first pass. After adjustment, lower literacy (P=.04) and being black (P=.03) were associated with requiring more passes through the consent process. Not speaking English as a primary language was associated with requiring more passes through the consent process in bivariate analyses (P<.01), but not in multivariable analyses (P>.05). After the second pass, most subjects (80%) answered all questions correctly. With a teach-to-goal strategy, 98% of participants who engaged in the consent process achieved complete comprehension. CONCLUSIONS: Lower literacy and minority status are important determinants of understanding consent information. Using a modified consent process, little additional education was required to achieve complete comprehension, regardless of literacy or language barriers.