The adsorption of proteins and synthetic polymers at the air-water interface (AWI) has broad significance in biomedicine and biotechnology. Protein behavior at the AWI can be guided to control the structure of the two-dimensional biopolymer film. In addition, synthetic polymers affect how plasma proteins act on implant or drug carrier surfaces, and can also decrease the potential for gas embolism. In this thesis, fluorescence microscopy was applied in combination with tensiometry and atomic force microscopy to study plasma proteins at the AWI alone and under the effect of synthetic polymers. First, the morphology of serum albumin layer controlled by the solution conditions was explored by fluorescence microscopy. Heterogeneity at the micron scale was observed for the protein film during adsorption and at reduced concentrations. Moreover, the competition for interfacial area between Pluronic surfactant F-127 and fibrinogen or serum albumin was studied by semi-quantitative confocal fluorescence methods. A transition stage where F-127 and protein underwent lateral phase separation was found. Two competing processes were revealed--the disintegration of protein-rich phase by F-127 and the coalescence of protein phase. Lastly, the interaction of immunoglobulin and the thin film of a widely used polydimethylsiloxane synthetic polymer was studied at the AWI. The compression state of the polymer film was shown to significantly affect protein adsorption and guide proteins into circular domain structures. Overall, this work has demonstrated the wide utility of fluorescence microscopy to study protein-protein and protein-synthetic polymer interactions at the AWI.