One of a series of sixteen knowledge transformation papers, this paper reviews data sources for objective evaluation of vocational education, including the need for such information and the problems associated with its use. First, a list is given of thirty-five data elements necessary to evaluate a skill training problem at the secondary, postsecondary, or adult level. Then, the needs are further broken down according to these three levels as well as the elementary level. Other elements that exist outside the school environment are also recognized and are found to be related to the economic impact of vocational education. The data sources are divided into the following information topics: (1) labor market, (2) scholastics, (3) demography and population characteristics, (4) economic impact, (5) facilities and equipment, (6) personnel and/or staffing, and (7) program. Limitations on using data collected in these areas involve accuracy, comprehensiveness, timeliness, scope, form, compatibility, and coordination. Other problems are found to exist in data collection, such as insufficient data sources, methodological difficulties, and duplication. The use of a computerized data system is stressed. Besides the five primary statistical sources named in the conclusion, Appendix A lists major secondary sources for the national, statewide, and local levels. Appendix B shows the lack of a complete basic evaluation data in a national EPD program. (ELG)