Effective, nonspecific interactions of lipid monolayers of octadecanoic acid, methyl octadecanoate, and octadecanol with aqueous neutral polymers of poly(vinylpyrrolidone), poly(vinyl alcohol), and poly(ethylene glycol) were investigated. These polymers dissolved in the subphase expanded surface monolayers at low surface pressures effectively (even at 10(-6) unit M), but did not disturb the molecular packing in their condensed phases. Fluorescence microscopic observations indicated that the aqueous polymers decreased the domain size of the monolayers and induced crystal growth on compression. Resistance of monolayers to collapse, as examined by monitoring area changes at constant pressures, showed that the polymers stabilized monolayers by suppressing the collapse process. However, the polymers did not accompany the monolayer in the Langmuir-Blodgett transfer onto solid surfaces. The absence of the polymer in the transferred film was confirmed by the quartz crystal microbalance technique, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Small concentrations of neutral polymers in the aqueous subphase facilitated transfer of neat lipid monolayers to homogeneous Langmuir-Blodgett films.