As ambulatory care practices face increasing pressure to implement electronic health records (EHRs), there is a growing need to determine the essential elements of a successful implementation strategy. HealthTexas Provider Network is in the process of implementing an EHR system comprising GE Centricity Physician Office-EMR 2005, Clinical Content Consultants (now part of GE), and Kryptiq Secure Messaging throughout all 88 practices in the Dallas-Fort Worth area and is hoping to extend the system to other practices affiliated with Baylor Health Care System as well. We describe the preimplementation clinical process redesign and quality improvement training that has been conducted networkwide in preparation for the introduction of the EHR, as well as the specific steps taken to prepare and train clinic staff for the integration of the EHR into daily workflows. The first pilot site, Family Medical Center at North Garland, implemented the system in May 2006. Based on both the positive aspects of this experience and the challenges we encountered, we identified 20 essential elements for successful implementation in the areas of site selection, implementation strategy, staff education and preparation, team project management, content, hardware and software, and workflow process. Broadly, we determined that 1) a pilot site's understanding of and willingness to work within the fluid nature of the implementation process during what is essentially a testing phase is a key ingredient in achieving success at the pilot site and in improving the process for later sites; 2) input from and representation of viewpoints of all types of EHR users during preimplementation decision making enables customization of the system and sufficient preplanning to ensure minimal workflow disruptions during and after implementation; and 3) a high level of technical and training support during the early days of implementation is invaluable.