Aggregation structures in organic gels and xerogels formed from l-glutamic acid-derived lipids were investigated by scanning and transmission electron microscopies, X-ray analyses, and 1 H NMR and IR spectroscopic methods. These analyses showed that the gels were produced through the formation of highly oriented aggregates based on a single layer and a remarkable development of their ® brous morphology. We also describe how the critical aggregation concentration can be observed at a concentration below the critical gel concentration by using a dye-complexation method with a cyanine dye, NK-77.