The equilibrium thicknesses and drainage have been measured of free liquid films, stabilized only by poly(vinylalcohol)(PVA) or partially esterified poly(methacrylic acid)(PMA-pe). The equilibrium thickness of PVA-films considerably exceeds twice the ellipsometric or the hydrodynamic thickness of one adsorbed layer. This is attributed to the dominant steric repulsion of isolated tails, a conclusion that is substantiated by theoretical arguments. The change in drainage behaviour of PMA-pe films as a function of pH correlates well with the conformational transition that this polyelectrolyte undergoes in the bulk and in the adsorbed state.