Various published measurements of the osmotic coefficient and the apparent molal enthalpy of aqueous CaCl2 are examined and correlated. It is found that CaCl2 shows an anomalous behavior near 5 molal. Below that molality the various properties are well represented by the usual ion-interaction equation with simple temperature dependent expressions for the second and third virial parameters. Information from neutron diffraction and crystal structure is considered in discussing the anomalous behavior at high molality.