The often astonishing material properties of crystalline biominerals are generally related to the hierarchical assembly of specifically interacting organic and inorganic components. To synthesize new materials with similar advanced properties applying nature's biomimeralization strategies we need to unravel the mechanisms of biologically and biomimetically controlled mineral formation. Since the literature is extensive this tutorial review is focussed on CaCO(3), the most abundant biomineral. We will first review the different approaches to biomimetic mineralization and describe the most recent advancements in the field. Subsequently the importance of in situ and time-resolved experiments, with their possibilities and limitations, is discussed with selected references.