Understanding the distribution of achievement levels of students' perf
ormance in the National Assessment of Educational Progress (NAEP) is a
ided through the use of the trilinear chart. In this article, this cha
rt is described and its use illustrated with data from the 1992 state
NAEP mathematics assessment. It is shown that one can see readily the
trends in performance for different demographic groups for all of the
44 participating jurisdictions simultaneously. lt is suggested that th
is graphical form may be useful in other contexts, as well.