The first observations of circumstellar CO emission from cool evolved giant stars using the Caltech 10.4 m submillimeter telescope are reported. New detections, some tentative, were made of 16 stars, mostly south of -20 deg declination. Among the objects detected are the nearby S star Pi1 Gru; the peculiar stars IRAS 15194-5115, IRAS 19500-1709, and IRAS 23321+6545; the supergiant OH/IR star VX Sgr; and possibly the WC10 Wolf-Rayet star CPD -56 deg 8032 - this observation helps establish the identification of cool WC10 stars with planetary nebula nuclei. The CO outflow velocity for VX Sgr is about 30 Km/s, while that measured by OH maser emission is 19 Km/s, showing that the wind velocity for VX Sgr continues to increase to very large distances from the star. The location of the peculiar cool stars on IRAS color-color diagrams and the detection of circumstellar CO suggests that they are proto-planetary nebulae. 39 references.