The National Assessment of Educational Progress (NAEP) is compared to the two studies of the National Educational Longitudinal Studies (NELS) Program--the National Longitudinal Study of the Class of 1972 (resurveyed in 1973, 1974, 1976, and 1979) and the 1980 High School and Beyond study (partially resurveyed and retested in 1982). The third phase of the NELS program, the National Education Longitudinal Study of 1988 (initiated in 1986) breaks new ground. Transitions into and through secondary school and the processes of program selection and tracking will be studied, and a less biased sample of dropouts will be included. There are advantages and disadvantages to greater integration and exchange of information between these studies. Five factors influencing the utility of the data collected in these two programs are reviewed: (1) Population definitions and sample designs are inconsistent and change over time. (2) The response burden upon institutions and individuals can be lessened by NAEP's use of matrix sampling and BIB spiralling. Coordination is needed to prevent schools from participating in both surveys at once, and to help in data exchange. (3) Data should be useful to educators and administrators at the state and local level. NELS allows states to survey supplemental data; this may also be useful for NAEP. (4) Data collection and processing costs may be helped by states' supplementary data collection and by increased efficiency. Otherwise, the required sample sizes would be too large and too costly. (5) Opportunities provided by new technology involve microcomputers, computer assisted testing, and computer assisted interviewing. (GDC)