Students in their first year choose three laboratories for rotations and spend one quarter in each (one quarter may be during the summer preceding or following the first year). The main purpose of these rotations is to allow students to investigate possible laboratories for their subsequent thesis research. They also give first-hand experience in a variety of techniques and approaches to biological problems. All rotations are performed in BMS member laboratories. Following completion of rotations, students select a lab in which to conduct research leading to a dissertation and award of the PhD degree.