The tectonic history of the Western Mediterranean region during the Oligocene and early Miocene is illustrated through a series of plate reconstructions, from chron C13n to chron C6n. The reconstructions are based on a new interpretation of published magnetic anomaly data and two-ships seismic data, and their integration with known geologic constraints, in order to determine style and timing of the back-arc extension processes in the Liguro-Provençal, Valencia, and Algerian basins. In particular, a new technique for the interpretation of the regional magnetic anomaly field allowed a determination of the instantaneous Euler poles associated to the motion of 11 microplates relative to Eurasia and Iberia. Furthermore, a quantitative analysis of the acoustic basement morphology and the balancing of deep crustal profiles were used to estimate the closure and pre-rift rotation angles associated to the Euler poles of opening of the Ligurian, Provençal, Valencia, and Algerian basins. This rigorous reconstruction of the geometry of the pre-rift continental margins could furnish important insights to the study of Mediterranean tectonics for older times.