A Vietnamese cook, a German journalist, and a Senegalese student–what did they have in common? They were all suspicious persons kept under surveillance by French colonial authorities in West Africa in the 1920s and 1930s. *Colonial Suspects* looks at the web of surveillance set up by the French government during the twentieth century as France’s empire slipped into crisis. As French West Africa and the French Empire more generally underwent fundamental transformations during the interwar years, French colonial authorities pivoted from a stated policy of assimilation to that of association. Surveillance of both colonial subjects and visitors traveling through the colonies increased in scope. The effect of this change in policy was profound: a culture of suspicion became deeply ingrained in French West African society. Kathleen Keller notes that the surveillance techniques developed over time by the French included shadowing, postal control, port police, informants, denunciations, home searches, and gossip. This ad hoc approach to colonial surveillance mostly proved ineffectual, however, and French colonies became transitory spaces where a global cast of characters intermixed and French power remained precarious. Increasingly, French officials–in the colonies and at home–reacted in short-sighted ways as both perceived and real backlash occurred with respect to communism, pan-Africanism, anticolonialism, black radicalism, and pan-Islamism. Focusing primarily on the port city of Dakar (Senegal), Keller unravels the threads of intrigue, rumor, and misdirection that informed this chaotic period of French colonial history.