The unique behavior of compounds confined at interfaces can be very different from those in bulk situations. Determining structure and chemical bonding at surfaces is central to continued progress in the field. This Faraday Discussion focusses on understanding the interaction of molecules with surfaces and their subsequent organisation, reactivity, or properties from both experimental and theoretical perspectives. It features contributions from scientists working on surface structuring with molecules, surface reactivity, characterisation, measurement of properties and modelling all of these features.