This award provides partial support for a conference on landmark longitudinal studies of the twentieth century. The conference will be hosted by the Henry A. Murray Research Center of Radcliffe College on April 23-24, 1999. The conference will bring together the principal investigators of ten of the country's most important longitudinal studies, who will be asked to talk about the interplay of investigator, study, study participants, historical context, and changing research fields. The major aims of the conference are to document the history of ten important, diverse and carefully chosen studies, to help determine which data sets are most worthy of preservation, and to identify the kinds of prospective research projects that will be needed in the twenty-first century. Other aims include teaching graduate students about this kind of study, stimulating interest in secondary analysis of these data sets, and disseminating knowledge of these landmark projects to the general public.