Measurements of electron transfer between singlet excited lipid-functionalized pyrene and alkyl-substituted dipyridinium cation have been carried out in the lipid-water interfacial region of both spread monolayers and vesicles. These studies have been conducted to evaluate the effects of limited-dimensionality on the kinetics involved. Zwitterionic dioleoylphosphatidylcholine (DOL) and negatively charged dioleoylphosphatidylglycerol (DOPG) have been used as the lipid hosts in this study. The functionalized compounds were 1-(10-(6(8)-octadecylpyrenyl)decanoyl)-2-hexanoylphosphatidylcholine (OPyPC), utilized as the donor, and an amphiphilic acceptor, 4-(N-hexadecylpyridinium-4-yl)pyridine chloride (CB+). It has been shown by monolayer compression studies that the rates of forward transfer in spread monolayers are sensitive to lipid organization and that the time-resolved quenching of pyrene fluorescence conforms well to Owen’s model for two-dimensional diffusion. The apparent dependence of the diffusion coefficient on surface pressure suggests some repositioning of CB+ in the interfacial region at higher surface pressures. mash photolysis measurements in vesicles demonstrate that electron transfer from the excited singlet state is more efficient than from the triplet. Further, the determination of back reaction shows both a short- and long-lived component for the reduced acceptor (CB) while the donor product cation (OPyPC(+)) disappears more quickly. This behavior indicates that the host lipid can act as a sacrificial donor for OPyPC(+).