Defining the functional distinctions between cells comprising the bone marrow has yielded fundamental insights into lineage ordering and drivers of blood cell production. A novel, highly granular and multi-dimensional molecular characterization of functional subsets of hematopoietic stem- and progenitor cells recently published in Cell Stem Cell (Cabezas-Wallscheid et al, 2014) will serve as a landmark and treasure trove for unanticipated insights into basic biology and the development of future targeted medicine.