AbstractSummary:This paper describes the behavior of some polysaccharides with well‐known chemical structures and in which the influence of cooperative secondary interactions play an important role. The roles played by hydrophobic and ionic interactions (including ionic selectivity) on polysaccharide conformation and gelation are discussed. Electrostatic attractions are also important in the complexes formed between surfactants and polyelectrolytes of opposite charge. Finally, van der Waals dipolar interactions and particularly hydrogen‐bond formation are examined. The role of hydrogen bonds in solubility, conformation, and especially the local stiffness of polysaccharides, but also in polymer–polymer complexes frequently obtained with polysaccharides, is developed.Repeat unit for a number polysaccharides.magnified imageRepeat unit for a number polysaccharides.