The chapter discusses the stability of soil pores and particles, which is crucial for optimal plant growth. It categorizes aggregates into macro- (> 250 μm) and micro- (< 250 μm) based on their stability against disruptive forces caused by rapid wetting. Microaggregates are prone to dispersion due to the adsorption of complexing organic acids that increase the negative charge on clays, while the binding action of polysaccharides, primarily bacterial mucilages, and multivalent cations enhance their stability. Macroaggregates are stabilized by plant roots, both living and decomposing, and their formation increases with grass growth and soil disturbance. Conversely, fallow periods lead to a decrease in macroaggregates. The chapter also highlights the role of organic materials in influencing dispersion-flocculation phenomena and the stability of macroaggregates, with specific examples from basaltic soils where organic matter content affects the point of zero charge (PZC) of clay particles.The chapter discusses the stability of soil pores and particles, which is crucial for optimal plant growth. It categorizes aggregates into macro- (> 250 μm) and micro- (< 250 μm) based on their stability against disruptive forces caused by rapid wetting. Microaggregates are prone to dispersion due to the adsorption of complexing organic acids that increase the negative charge on clays, while the binding action of polysaccharides, primarily bacterial mucilages, and multivalent cations enhance their stability. Macroaggregates are stabilized by plant roots, both living and decomposing, and their formation increases with grass growth and soil disturbance. Conversely, fallow periods lead to a decrease in macroaggregates. The chapter also highlights the role of organic materials in influencing dispersion-flocculation phenomena and the stability of macroaggregates, with specific examples from basaltic soils where organic matter content affects the point of zero charge (PZC) of clay particles.