Publisher Summary In addition to their use as drug carriers, liposomes are frequently employed as model membranes in the study of biological processes. This is because liposomes are easy to prepare, the researcher can define the lipid matrix, and identification of membrane degradation products is not clouded by the complexity of biological systems. This chapter discusses the photolabile liposomes as carrier. The liposomes have been used to study the photodynamic action (membrane damage) of various chromophores, and the phototoxicity of drugs. In these studies membrane damage was monitored by the release of entrapped solutes. Light-induced leakage of various markers has been reported for different liposome systems. The chapter discusses light-sensitive liposomes with the intent of studying their in vitro and in vivo drug-delivery potential. The light-sensitive liposomes described in the report elicit the fastest light induced release rates reported and have been called photosomes. Experimental considerations in preparing and evaluating vesicles that release entrapped solutes on exposure to light are discussed.