Molecules are held together by chemical bonds. The CH-( interactions deals with the interactions between two bonds, which contributes to the shape and reactivity of the molecule. This book presents an overview of the experimental basis, theoretical background, and nature of the CH-( Interactions. The CH-( Interaction refers to a weak attractive force that originally was inferred from structural data obtained by spectroscopy. The characteristics of this weak force are compared to those of other hydrogen bonds.