In 1925-26, the future Nobel prize-winner Max Born presented two series of lectures at the Massachusetts Institute of Technology: one on the structure of the atom, the other on the lattice theory of rigid bodies. This volume contains the text of every lecture from both series, offering a remarkable look at the transition from the quantum theory of Bohr to a new direction in atomic dynamics. "At the time I began this course of lectures," Born writes, "Heisenberg's first paper on the new quantum theory had just appeared. Here his masterly treatment gave the quantum theory an entirely new turn. The paper of Jordan and myself, in which we recognized the matrix calculus as the proper formulation of Heisenberg's ideas, was in press, and the manuscript of a third paper by the three of us was almost completed." In the course of the lecture series, Born introduced new developments as they occurred: Pauli's fourth quantum number, Dirac's formalism, and elements of his own work on a general operational calculus. Appropriate for upper-level undergraduates and graduate students, Problems of Atomic Dynamics represents the foundations of quantum theory and offers a vivid look at science in the making, presenting clear-cut results that have withstood decades of experimentation.