This chapter reviews the growing body of data on the binding interactions between dendrimers and two types of well-established molecular hosts: cyclodextrins and cucurbit[n]urils. Dendrimers are highly branched macromolecules to which functional groups can be attached in spatially defined locations. The attachment of guest functional groups to dendrimers allows the investigation of their binding interactions with freely diffusing hosts/receptors. The effect of dendrimer size on the thermodynamics of these host-guest reactions varies widely depending on factors described here. In optimum cases, it is possible to use these binding interactions to exert redox control on dendrimer self-assembly and even control the size of the resulting assemblies.