Biological materials found in Nature are tough and strong—examples of the mineralized kind range from sea shells to bones and teeth. These biological materials serve as examples of complex, functional materials that are constructed from organic and inorganic components along a hierarchical architecture. In order to create proper conditions for growth and development, biology has adapted mechanisms to sequester and organize local chemical environments. These include processes that regulate pH, concentration, and organic-inorganic interactions—all necessary events for proper cellular and mineral growth processes. Recent evidence reveals the presence of nanoscale mineral precursors that are intermediate phases in mineralization; clustering into assemblies that template and drive nucleation events along specific pathways. Several groups have shown that interactions with these intermediate phases drive mineralization along diverse pathways. These intermediate phases support the existence of non-classical routes to crystallization. The characteristics of these assemblies are crucial in their regulation of nucleation and crystal growth mechanisms. With these observations, we can begin to formulate approaches that utilize these biological strategies in creating synthetic, sustainable bulk functional crystalline materials with tunable materials properties.