This document provides an introduction to the Encyclopedia of Human Resources Information Systems: Challenges in e-HRM. It is edited by Teresa Torres-Coronas and Mario Arias-Oliva and published by IGI Global. The encyclopedia rigorously analyzes key critical HR variables and defines previously undiscovered issues in the HR field. It contains contributions from over 150 authors from around the world on topics related to personnel management, information storage and retrieval systems, management information systems, and the management of knowledge workers.