Cubic [Ru-2(O2CMe)(4)](3)[Cr(CN)(6)] prepared from water has two interpenetrating lattices and exhibits anomalous magnetic hysteresis, saturation magnetization, out-of-phase alternating current (AC) susceptibility, chi"(T), and zero-field-cooled/field-cooted temperature-dependent magnetization data with respect to either the material prepared from acetonitrile or the layered two-dimensional (2D) [Ru-2(O2CBU')(4)](3)[Cr(CN)(6)]center dot 2 H2O prepared from water. These unexpected properties are attributed to the presence of the interpenetrating lattices and reveal that, albeit uncommon, interpenetrating-lattice-structured materials can stabilize new cooperative magnetic behavior.