The purpose of a chemical structure diagram is to convey information— typically the identity of a molecule—to another human reader or as input to a computer program. Any form of communication, however, requires that all participants understand each other. Recommendations are provided for the display of two-dimensional chemical structure diagrams in ways that avoid ambiguity and are likely to be understood correctly by all viewers. Examples are provided in many areas, ranging from issues of typography and color selection to the relative positioning of portions of a diagram and the rotational alignment of the diagram as a whole. Explanations describe which styles are preferred and which should be avoided. Principal recommendations include: • Know your audience: Diagrams that have a wide audience should be drawn as simply as possible. • Avoid ambiguous drawing styles. • Avoid inconsistent drawing styles.