The development of the "Directories of Unpublished Experimental Mental Measures" is traced. Two decades ago, the senior author of this research began the compilation of a list of non-standardized experimental test instruments developed by behavioral and social sciences researchers. Making this information available was intended to help researchers in need of tests, and to keep them from reinventing the wheel. Volume 1 of the "Directories" was a pilot study to determine the feasibility of the project. Using a 22-category system to classify tests and an exhaustive keyword subject index, Volume 1 was published in 1974, containing 339 non-standardized and unpublished experimental test instruments. Volume 2 was published in 1978 with an additional 695 instruments from an expanded list of research journals. Volume 3 was published in 1982 and contained 561 experimental tests gleaned from the 1973 issues of 46 journals. Volume 4 was published in 1985 to cover tests described in the 1974-80 issues of 46 professional journals. Volume 5, published in 1990, contained tests from the 1981-85 issues of 37 journals. Volume 6 is currently being compiled to assist researchers by providing a reservoir of research topics and stimulating further research on various topics. There is a five-item list of references. (SLD)