The Proceedings of the Twelfth International Basement Tectonics Conference continues an emphasis on tectonic problems of the older continental crust. While the evolution of the southern margin of the North American plate receives needed attention, problem areas of the Appalachians and of the Italian region are also treated. Finally methods of geophysical probing of upper crustal structure are explored. Geoscientists from seven different countries present the results of their research. Full papers in this book target the Llano region of Texas, the Southern Oklahoma Aulacogen, the northern Reading Prong of the northeastern USA, the Sardinian-Corsican Massif, the El-Eredyia area of Egypt, and seismic imaging beneath thrust blocks. The shape of plutons is analyzed with respect to crustal magma traps and magma driving pressure for a specific site in an extensional setting. Shorter communications include studies on fracture development, both laboratory studies and field studies, propagation and reactivation of faults, and lithological and geochemical studies of basement terranes.