BackgroundTo estimate the efficacy of interventions to improve healthy eating, valid measures are essential. Although simple dietary intake tools have been developed with other populations, few have been culturally tailored and assessed for validity and reliability among Navajo.ObjectivesThis study aimed to develop a simple dietary intake tool tailored to Navajo culture, derive healthy eating indices, and assess their validity and reliability in Navajo children and adults and to describe the process used to develop this tool.MethodsA picture-sort tool using typically consumed foods was developed. Elementary school children and family members provided qualitative feedback in focus groups, used to refine the tool. Next, school–aged children and adults completed assessments at baseline and follow-up. Baseline behavior measures including child self-efficacy for fruits and vegetables (F&V) were examined for internal consistency. Healthy eating indices were derived from intake frequencies from picture sorting. The convergent validity of the indices and behavior measures for children and adults were examined. The reliability of the indices at the 2 time points was derived using Bland-Altman plots.ResultsThe picture-sort was refined from feedback provided by the focus groups. Baseline measures from 25 children and 18 adults were obtained. In children, a modified Alternative Healthy Eating Index (AHEI) and 2 other indices from the picture-sort were correlated with self-efficacy for eating F&V and had good reliability. In adults, the modified AHEI and 3 other indices from the picture-sort had significant correlations with adult abbreviated food frequency of F&V or obesogenic dietary index and had good reliability.ConclusionsThe Navajo foods picture-sort tool developed for Navajo children and adults is proven to be acceptable and feasible to implement. Indices derived from the tool has good convergent validity and repeatability, supporting use in evaluating dietary change interventions in Navajo, with the potential for broader use of the approach in other underserved populations.