In this study, we examine factors that influence users’ post-adoption switching between technology products that are near perfect substitutes. The recent introduction of Mozilla Firefox Web browser provided an ideal empirical setting for this study. Drawing upon literature on post-adoption user behavior, consumer behavior, and online consumer research, we proposed a research model and validated it using cross-sectional field data collected from 306 users on their decisions to switch from Microsoft Internet Explorer to Mozilla Firefox. Findings suggest that user satisfaction and breadth of use of the incumbent product are negatively associated with switching behavior, and perceived ease of use, relative advantage, and perceived security of the substitute product are positively associated with switching behavior. This study contributes to both research and practice by advancing our understanding of users’ post-adoption behavior in general and their switching behavior on Web-related technology products in specific.