Solutions of poly(vinyl alcohol) (PVA) and polysaccharide with sodium borate (SB) are investigated as a model system for associating polymers which exhibit shear‐induced fluid structure and shear‐thickening rheology. Certain combinations of PVA and SB concentrations are shown to result in fluids that exhibit a viscosity maximum followed by shear thinning as shear rate is increased. Stress saturation is often observed in the shear‐thinning region. A significant hysteresis is also reported in which higher viscosities and lower shear rate for the viscosity maximum are observed in steady‐state measurements made while decreasing shear rate in a stepwise manner. Boron nuclear magnetic resonance spectra are shown to be useful for elucidating the nature of the borate/hydroxyl‐dyad complexes, including their stereoselectivity. Boron resonance peaks allow quantitative determination of the number of complexes. Dynamic mechanical properties are included, and a physical picture of network structure building and breaking during flow of associating polymers is discussed.