Multiple lines of investigation have demonstrated that the immune system plays an important role in preventing tumor initiation and controlling tumor growth. Accordingly, many cancers have evolved diverse mechanisms to evade such monitoring. While multiple immune cell types mediate tumor surveillance, recent evidence demonstrates that macrophages, and other phagocytic cells, play a key role in regulating tumor growth through phagocytic clearance. In this review we highlight the role of tumor immune evasion through the inhibition of phagocytosis, specifically through the CD47–signal-regulatory protein-α pathway, and discuss how targeting this pathway might lead to more effective cancer immunotherapies.