The relatively modest energetic splitting of the d-orbitals by the surrounding crystal field is comparable to the repulsive energy of putting two electrons in the same orbital, the spin pairing energy. This gives rise to electronic states where the electrons singly occupy all five d-orbitals before pairing (high-spin configuration) as well as states where the lower lying d-orbitals are completely filled before moving onto the higher energy d-orbitals (low-spin configuration). In the first half of this lecture this topic is explored. In the second half, Jahn-Teller distortions are discussed. These are electronically driven structural distortions that lower the symmetry of the molecule. This lecture was designed and delivered by Patrick Woodward for use in the course Solid State Chemistry (Chem 7330) at Ohio State University.