For mammals to develop properly, master regulatory genes must be repressed appropriately in a heritable manner. This review concerns the Polycomb Repressive Complex 1 (PRC1) family and the relationship between the establishment of repression and memory of the repressed state. The primary focus is on the CBX family of proteins in PRC1 complexes and their role in both chromatin compaction and phase separation. These two activities are linked and might contribute to both repression and memory.