This is a review of quantum chemical, statistical-mechanical, electrostatic, and crystal chemical studies of phyllosilicates. Atomic-level studies have examined the structure and bonding within phyllosilicate layers, the effects of cation substitution on bonding and charge distribution, the structure of water, and the distribution of cations in the interlayer, and the bonding between phyllosilicate layers. The major needs for future research are statistical-mechanical simulations of ion exchange reactions, electron transport in transition-metal-containing phyllosilicates, structure and bonding at phyllosilicate edges, and mechanisms of crystal growth and dissolution.