Despite the widespread use of eHR systems, surveys show that there may be a number of problems associated with their design and implementation [CedarCrestone (2007). CedarCrestone 20072008 HR systems survey: HR technologies, service delivery approaches, and metrics. Available at www.cedarcrestone.com/research.php. Retrieved July, 2008]. In an effort to overcome these problems we expanded the model of eHR acceptance and effectiveness developed by Stone. Stone-Romero, & Lukaszewski [Stone, D. L. Stone-Romero, E. F., & Lukaszewski, K. (2006). Factors affecting the acceptance and effectiveness of electronic human resource systems. Human Resources Management Review, 16, 229-244]. The expanded model provides a more detailed discussion of the communication processes underlying these systems including the effects of media and message characteristics. In addition, we offer a number of testable hypotheses based on the model that can be used to guide future research on eHR systems. (C) 2008 Elsevier Inc. All rights reserved.