This volume contains contributions presented at the 12th International Conference on High Magnetic Fields in Semiconductor Physics. In order to give an overview, 37 lecturers not only reviewed the latest results in their field, but also gave a general introduction. The rapid development of semiconductor physics and technology during the last few years has resulted in an extensive application of high magnetic fields in both fundamental and applied research; more than 160 contributed papers were presented as posters.Sixteen years after its discovery, the quantum Hall effect (QHE) is still a...