The characteristics of molecular organization, aggregation, and cis-trans isomerization of azobenzene moieties, confined in the hydrophobic region of monolayers of an amphiphilic azobenzene derivative (A820Py) at the air/water interface, have been investigated. As a result of conformational changes accompanied by the isomerization process, the molecular packing within the monolayer at constant surface area and thereby the molecular organization show pronounced changes. The surface-enhanced UV-vis reflection spectra of A820qr monolayers show the presence of both monomers and H aggregates. Cis-trans isomerization leads to changes in the resonant reflection spectrum, the surface potential, and the Brewster angle reflectivity of the monolayer. The isomer composition of the photostationary states of pure A820Py monolayers has been determined through the analysis of UV-vis reflection spectroscopic data. The ratio of quantum yields of photostationary states of A820Py in solution and in monolayers have been compared. The kinetics of the cis-trans isomerization process in the monolayers have been followed by measuring the resonant reflection, the surface potential, and the Brewster angle reflectivity. The composition of the photostationary states has been analyzed in terms of the Fischer method. The monolayers prepared at the air/water interface have been transferred to solid substrates such as glass or quartz plates. A persistent pattern was written in the single monolayer by exposing it to actinic radiation through a mask. Brewster angle microscopy was used to visualize the created microscopic pattern of trans and cis isomers.