All living systems produce complex carbohydrates as an energy source, protective coat, or adhesive for cell attachment. Polysaccharides displayed on the cell surface are secreted by diverse mechanisms that either directly couple polymer synthesis to export or involve dedicated transporters capable of moving high molecular weight polymers across the plasma membrane. Microbial cellulose biosynthesis and the ABC transporter-mediated secretion of O-antigens exemplify two fundamentally different translocation mechanisms. Both pathways contribute to the formation of protective coats frequently produced by microbial pathogens to reduce the efficacy of their hosts’ innate immune responses. Using structural and functional analyses, we obtained detailed insights into diverse polysaccharide secretion mechanisms.