Smith examines the longstanding relationship between socialists and communists in France, Italy, and Spain—three Latin European countries with historically significant communist parties rivaling socialists for domination of the political Left. In particular, the distinction is made between periods of conflict and periods of cooperation since 1920, but especially since the 1960s, and the critical junctures when a party (or specifically its leader) chose a given strategic direction in a path-dependent way. Smith's explanation is based on the effects of national political institutions, the culture of specific parties, and individual party leaders. Such breadth is crucial to a full explanation and is a key strength of this book. The conclusions then extend the analysis briefly to Greece and Portugal. In addition to examining the building of alliances, antecedent focus is given to the comparative nature of party organizations. This is an excellent work of comparative politics, clearly written and based on detailed research and fieldwork. It provides insights on each country as well as west European politics in general. Brief historical counterfactuals are also suggested. Definitely recommended for both political scientists and historians. Summing Up: Highly recommended. Upper-division undergraduate, graduate, and research collections.