The Comparative Systems Laboratory (CSL) proposed to deal with the problems of testing retrieval systems by examining a number of processes involved in such systems, with particular attention to the human factor. It is hoped that the results of the project will be useful in refining methodologies for experimentation with information retrieval (IR) systems and in providing clues for the more effective design and redesign of operating IR systems. The second part of the final report of the project includes: (1) a summary of the experiments conducted, (2) a description of the method of analysis of results and a discussion of some problems encountered in analysis, (3) a description of the data base of the experiment in terms of questions, users and answers, (4) results pertaining to each of the variables tested (sources of indexing, indexing languages, question analysis, searching strategies, and formats of output), (5) specific, generalizable, and speculative conclusions drawn from these results, and (6) recommendations for future research on testing retrieval systems and on establishing relations between testing and practice. A list of CSL technical reports and additional publications is appended. (Author/JB)