Secretory IgA (SIgA) plays a crucial role in protecting the intestinal epithelium from enteric pathogens and toxins. It achieves this through immune exclusion, where SIgA blocks pathogens from accessing epithelial receptors, entrap them in mucus, and facilitates their removal. SIgA also functions in mucosal immunity and intestinal homeostasis by directly quenching bacterial virulence factors, influencing the composition of the intestinal microbiota, promoting retrotransport of antigens to dendritic cells, and downregulating proinflammatory responses. Recent studies have revealed that SIgA can block pathogen attachment to epithelial cells through steric hindrance and receptor binding, and it can also act as a decoy to prevent pathogen binding. Additionally, SIgA has been shown to influence the composition of the intestinal microbiota and promote the uptake of antigens from the intestinal lumen to DC subsets in gut-associated lymphoid tissues. SIgA's role in maintaining intestinal homeostasis is further highlighted by its ability to reduce proinflammatory responses and control allergic reactions. The complex glycan arrays on polymeric IgA and bound secretory component contribute to its multifaceted activities. Overall, SIgA's intricate mechanisms and diverse functions are essential for maintaining the integrity of the intestinal barrier and immune homeostasis.Secretory IgA (SIgA) plays a crucial role in protecting the intestinal epithelium from enteric pathogens and toxins. It achieves this through immune exclusion, where SIgA blocks pathogens from accessing epithelial receptors, entrap them in mucus, and facilitates their removal. SIgA also functions in mucosal immunity and intestinal homeostasis by directly quenching bacterial virulence factors, influencing the composition of the intestinal microbiota, promoting retrotransport of antigens to dendritic cells, and downregulating proinflammatory responses. Recent studies have revealed that SIgA can block pathogen attachment to epithelial cells through steric hindrance and receptor binding, and it can also act as a decoy to prevent pathogen binding. Additionally, SIgA has been shown to influence the composition of the intestinal microbiota and promote the uptake of antigens from the intestinal lumen to DC subsets in gut-associated lymphoid tissues. SIgA's role in maintaining intestinal homeostasis is further highlighted by its ability to reduce proinflammatory responses and control allergic reactions. The complex glycan arrays on polymeric IgA and bound secretory component contribute to its multifaceted activities. Overall, SIgA's intricate mechanisms and diverse functions are essential for maintaining the integrity of the intestinal barrier and immune homeostasis.