"Square-within-a-square": The first Cr–Dy single-molecule magnet (SMM) with an energy barrier to spin reorientation of 15 K is presented. The anisotropy in this octanuclear compound arises from the orientations of the four DyIII centers (dark blue), which, in conjunction with the contributions from the CrIII centers (green), leads to the SMM behavior. Detailed facts of importance to specialist readers are published as "Supporting Information". Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

An Octanuclear [CrIII4DyIII4] 3d–4f Single‐Molecule Magnet