Two papers are included as Part Four of this report on Salton's Magical Automatic Retriever of Texts (SMART) project report. The first paper: "A Controlled Single Pass Classification Algorithm with Application to Multilevel Clustering" by D. B. Johnson and J. M. Laferente presents a single pass clustering method which compares favorably with more expensive clustering algorithms. The method is tested using the ADI collection of 82 documents and the Cranfield 424 Collection. The results are compared to full search and to results obtained by searching clusters produced by Dattola's algorithm. The second paper: "A Systematic Study of Query-Clustering Techniques: A Progress Report" by S. Worona describes an experiment using various techniques of query clustering on the Cranfield 424 document collection and gives some preliminary results. Several methods of evaluating the performance of clustered searches in the context of query-clustering are discussed. Some observations are also made concerning use of the SMART system as implemented at Cornell University. (For the entire SMART project report see LI 002 719, for parts 1-3 see LI 002 720 through LI 002 722, for part 5 see LI 002 724.) (NH)