Synthetic receptors are modern tools for investigations into the forces involved in recognition. A widely exploited class of receptors are the resorcin[4]arene-based cavitands and capsules. This critical review (71 references) describes the evolution of water-soluble versions of these structures, along with insights the resulting host-ndash complexes have provided with regard to complexation driving forces in water. An emphasis has been placed on the influence of host structure on guest affinity and dynamics.