Abstract Diagrams are unquestionably powerful tools. A multitude of studies investigate the relative usefulness of different types of diagrams (e.g. Larkin and Simon, 1987; Vessey and Galletta, 1991; Vessey and Conger, 1994; Jones and Schkade, 1995). However, analysis and research directed at empirically identifying and synthesizing basic components of diagram clarity, are rare. This study integrates isolated findings related to diagram clarity and experimentally investigates their application. The research utilized comes primarily from the Cognitive Information Processing (CIP) and Information Theory (IT) streams. Accordingly, the approach here is termed CIPIT. The set of CIPIT rules presented here represent a foundational framework for basic diagram clarity. The utility of the CIPIT rules are investigated experimentally via applying the CIPIT rules to one type of diagramming technique, the Data Flow Diagram (DFD). The experiment is carried out to investigate the clarity of a CIPIT-based DFD relative to a non-CIPIT DFD. Diagram clarity is measured objectively in terms of both speed of comprehension and the amount of comprehension. A questionnaire using likert-scale items is used to capture users' attitudes about the two diagrams. The results indicate a strong significant effect (increased clarity) for the CIPIT-based DFD.