This community-based participatory research (CBPR) project used a collaborative process to develop a culturally relevant workbook for parents of overweight children. We followed a mixed methods iterative process to assess clear communication using a CBPR approach. Materials were evaluated using readability tests, the Clear Communication Index (CCI), and the Suitability Assessment of Materials (SAM). In addition, we used surveys and focus groups to investigate parents' perceptions and gather feedback from delivery staff using the workbook. While workbook materials maintained adequate grade reading levels, our iterative process and the use of CCI and SAM led to significant improvements in (a) clearly communicating the objectives of the program, (b) being culturally relevant, and (c) reaching a high satisfaction among users. These findings suggest that evaluative measures for written materials should move beyond readability and need to account for level of clarity and cultural appropriateness of messages. Furthermore, we found that that an iterative process to intervention's material development using clear communication strategies while involving community members, parents, and research partners can lead to workbook materials that are culturally relevant to the target audience, and better communicate program objectives. Finally, this is a potentially generalizable process for improving clear communication of written health information materials.