Understanding the transition from a continental to an oceanic rift, the earliest stages of seafloor spreading, and the formation of passive margins, is a major challenge in the Earth Sciences. The Red Sea/Gulf of Aden region is a natural laboratory where these questions can be uniquely addressed. This session aims at discussing models of kinematic evolution, mantle flow, rift-drift transition for the system of tectonic plates surrounding the Red Sea, the Gulf of Aden, and the Afar region. Contributions from Seismology, Plate Kinematics, Mantle Geodynamics, Marine Geophysics, Potential Fields Geophysics, Structural Geology, Geochemistry, and Petrology are welcome. (solicited people: Marco Ligi, marco.ligi@bo.ismar.cnr.it; Sigurjón Jónsson, sigurjon.jonsson@kaust.edu.sa)