Recent advances in technology provide support for multisite, Web-based data-entry systems and the storage of data in a centralized location, resulting in immediate access to data for investigators, reduced participant burden and human entry error, and improved integrity of clinical trial data. The purpose of this article was to describe the development of a comprehensive, Web-based data management system for a multisite randomized behavioral intervention trial. Strategies used to create this study-specific data management system included interdisciplinary collaboration, design mapping, feasibility assessments, and input from an advisory board of former patients with characteristics similar to the targeted population. The resulting data management system and development strategies provide a template for other behavioral intervention studies.