Abstract: This paper describes VAST, a prototype Visualisation and Analysis of Similarity Tool, which tutors can use to investigate student submissions for intra-corpal plagiarism. VAST displays a pair of student submissions and a graphical representation of their similarity, allowing tutors to navigate directly to areas of potential plagiarism. It improves on the human eye approach by identifying similarities a tutor might otherwise miss and saving investigative time. VAST is demonstrated using noise-free synthetic texts and actual student submissions containing intra-corpal plagiarism. Associated ideas, including similarity visualisations, similarity intersections and the Four-Stage Plagiarism Detection Process are also introduced.