The term ‘self-assembled monolayer’ (SAM) refers to robust monolayer films, such as alkylsilanes on silica or alkanethiols on gold, that spontaneously form on solid substrates from dilute solutions of adsorbates. They usually contain long alkyl chains that screen the properties of the substrate from that of the monolayer-liquid interface. Organic synthesis provides an almost limitless variety of different functional groups, or combinations of functionalities, at the surface of the monolayer. The synthesis, characterisation and properties of SAMs of thiols on gold is described in a series of publications with George Whitesides in the late 1980’s and early 1990’s. My group is no longer actively engaged in SAM research, though we still use SAMs as a tool for controlling wetting and adsorption at solid–liquid interfaces.