Although phenomena such as host-guest inclusion complex formation, the ability of detergents to solubilize otherwise insoluble solids in water, the formation of phospholipid bilayers and membranes, and the spreading of oil or amphiphilic molecules to give a monomolecular film at the air-water interface, have been long recognized, recent advances in structural characterization and spectroscopic techniques have led to a better definition of the interfaces involved in these phenomena and to a resurgence of interest in reactivity at these interfaces. In this tutorial we will focus on recent studies and developing possibilities for controlling photochemical and photophysical processes in layered Langmuir-Blodgett (LB) assemblies fabricated from sequential transfer of monolayers formed at the air-water interface to rigid supports.