Studies on the assembly of metal-organic frameworks (MOFs) have uncovered methods to build extended structures from molecular building blocks.1-3 The synthesis of a new type of porous material using strategies based on the expansion and decoration of vertexes in basic nets has demonstrated the wide scope of this chemistry.4 In particular, crystalline MOFs that maintain their open structure in the absence of guests can perform highly selective separations.5 Most MOFs have been constructed from simple unbranched connectors, such as 1,4-benzenedicarboxylate and 1,3,5-benzenetribenzoate.4a In contrast, branched connectors, such as small dendrimers, have not been used to prepare MOFs because these connectors are more flexible. This flexibility could impede crystallization and characterization by single-crystal X-ray diffraction.6 Yet, crystalline metal-organic dendrimer frameworks (MODFs) generated from branched linkers such as small dendrimers would (a) provide information on dendrimer structure and (b) allow construction, from nanometer-sized building blocks, of well-defined frameworks with chemical and physical properties derived from those of the organic units. We report the synthesis, crystal structure, and sorption chemistry of the first MODF: