An ideal heterogeneous scaffold would, like enzymes, offer precise control over the active site nuclearity and metal-metal distance, as well as the identity and flexibility of the primary coordination sphere. These complex structural requirements represent an exciting opportunity for metalorganic frameworks (MOFs), a class of porous materials characterized by high structural and chemical tunability. Multiple strategies to install homo-and heterobinuclear metal active sites on MOF surfaces have been reported, and these prior examples can be roughly divided into two categories. In the first approach, multinuclear metal nodes are used directly as the catalytic centers. Coordinatively unsaturated binuclear metal nodes can be used without further modification, while larger nuclearity nodes, such as 1D chains, must be converted into site-isolated bimetallic sites through the synthesis of mixedmetal variants. In the second approach, bimetallic active sites are postsynthetically grafted onto the pore walls. Reactive surface hydroxyl sites, Lewis acidic metal cations, or organic functional groups on the ligand struts have all been used as the points of attachment. In the absence of pre-formed clusters or highly constrained binding pockets, 11 complex metal speciation is often observed in both approaches.