Main-group-semiconductor clusters are attractive atomically precise precursors for materials design. In particular, magic-sized clusters, those with elevated thermodynamic stability relative to other clusters of similar size, have been implicated as important intermediates in the synthesis of semiconductor nanostructures. A survey of the literature on the intermediacy of clusters in nanomaterial synthesis reveals two predominant mechanistic trends: monomer-driven growth and cluster assembly. In this Forum Article, we compare and contrast the systems, in which these mechanisms are operative, and attempt to extract the emerging design principles governing these transformations. Additionally, we highlight the gaps in our understanding of this emerging area of science and provide a roadmap for future reaction development.