Azobenzene derivatives are excellent candidates for optical switching systems, due to their facile and reversible photoisomerization. However. the chromophores are usually aggregated in Langmuir-Blodgett films, which suppresses this cis-trans isomerization. Here is reported the anchoring of palmitoyl and azobenzene functions to a fifth-generation dendrimer (see Figure) to yield very stable monolayers that show reversible photoinduced switching.