Simultaneous common volume measurements of mesospheric Ca, Na, and temperature profiles were conducted at Urbana, Illinois (40¿N, 88¿W), from late October 1992 to January 1993. The Ca layer abundance varied between 2.1--10.7¿107 cm-2, with an average of 6.3¿107 cm-2. The Na abundance averaged 7.2¿109 cm-2, or approximately 110 times that of Ca. The Ca layer centroid height varied between 90.8 and 92.5 km, with an average value of 91.8 km, and was on average 0.2 km higher than the Na layer centroid height. The rms widths of the Ca and Na layers averaged 3.5 and 4.7 km, respectively. No substantial sporadic Ca or sporadic Na layers were detected during our observations. Considerable gravity wave activity was observed in the Ca, Na, and temperature profiles on December 21--22, 1992. The relative Ca and Na density perturbations are in phase with temperature perturbations on the bottom side of the layers, and out of phase on the topside, consistent with theoretical predictions. Relative Ca density perturbations are larger than those of Na by a factor of 2 on this night. Our measurements are compared with the only previous lidar measurements of mesospheric Ca conducted in France by Granier et al. <1989>. ¿ American Geophysical Union 1995