The development and maintenance of multicellular organisms require the precise spatial and functional organization of diverse cell types. While initially dedicated to growth, this organization shifts in mature organisms to prioritize tissue homeostasis and long-term integrity. Central to this process are surveillance mechanisms that maintain cellular fitness by preventing the accumulation of suboptimal or damaged cells. One such mechanism, termed “cell competition,” has been increasingly recognized as a critical regulator of cellular quality control. Characterized by differential growth rates and the active removal of "loser" cells upon contact with more robust "winners," cell competition defines a context-dependent process where cellular status is determined relative to the fitness of the surrounding niche. In this lecture, we will examine the emerging role of innate immune cells as active mediators of cell competition within the hematopoietic system. We will specifically discuss how these immune populations influence cellular fitness and conclude by outlining future strategies and experimental models to study the regulation of stem cell clonality in health and disease.