The microstructures of several cobalt-rare earth magnet alloys from various laboratories were examined by transmission electron microscopy (TEM). The magnets varied in alloying elements and inz, the ratio of transition-metal to rare-earth atoms. Matsushita magnets withzsim8had a relatively featureless microstructure. Toshiba magnets withzsim7contained a fine cellular microstructure, and Brown-Boveri magnets withz=7.8contained fine isolated precipitates plus a partly-formed cellular structure. These observations are consistent with magnetization hehavior, which indicated nucleation-controlled coercivity for thezsim8magnets and pinning-controlled coercivity for thezsim7andz=7.8magnets. Results are compared with earlier TEM studies.