This book constitutes the refereed proceedings of the 8th International Conference on the Theory and Application of Diagrams Diagrams 2014 held in Melbourne VIC Australia in July/August 2014. The 15 revised full papers and 9 short papers presented together with 6 posters were carefully reviewed and selected from 40 submissions. The papers have been organized in the following topical sections: diagram layout diagram notations diagramming tools diagrams in education empirical studies and logic and diagrams.