This article examines the shifts in Information Systems (IS) research from a positivist to interpretive to sociomaterial paradigm by demonstrating how the shifts reflected the move from substantialist towards process metaphysics. Such metaphysical grounding provides a foundation for deeper understanding of paradigm differences and the struggles when shifts occur. After a brief historical overview of substantialist and process metaphysics and a summary of their key assumptions, the article explores paradigm shifts in IS research and highlights the underlying metaphysical nature of surrounding difficulties and controversies. The article advances the paradigm debate by drawing attention to the metaphysical nature of paradigmatic shifts in IS research and by opening up intellectual space for conceiving and understanding novel research approaches beyond Burrell and Morgan’s model [1].