The formation of rifted continental margins by extension of continental lithosphere leading to seafloor spreading is a complex and still poorly understood component of the plate tectonic cycle. New observations and modelling allow us to investigate the underlying processes. Key questions that need to be resolved include 1) factors that control the geometry and crustal architecture or rifted margins, 2) the role of strain localisation and strain partitioning throughout the rift history, 3) factors controlling the 3-dimensional geometry of rifts and passive margins, 4) processes responsible for anomalous vertical motions during basin evolution such as phase changes or small scale convective instability of the mantle lithosphere, 5) fundamental controls on the magmatic or a-magmatic nature of rifts and passive margins, 6) interaction between surface processes, tectonics, and climate during rift-passive margin evolution. We encourage abstracts that offer new insights into crustal and lithospheric architecture and processes underlying rifting and passive margin formation as well as smaller scale studies of individual sedimentary basins, using constraints from observations and modelling.