This research uses item response theory for the investigation of diffe
rential item functioning (DIF) and examines the advantages of using a
multivariate external criterion to match examinees from the various su
bpopulations. An attempt was made to select a set of unbiased items to
comprise the matching criterion. Expected course grades provided by t
he students' teachers were examined and found to function similarly ac
ross sex and race subgroups and were incorporated into the matching cr
iterion. The inclusion of teachers' grades provides additional informa
tion in the extreme proficiency ranges and has the potential to enhanc
e the validity of subgroup comparisons and inferences of possible item
bias. The use of an external matching criterion allows test developer
s to embed the same short, designated anchor in multiple test forms, t
hereby avoiding the circularity inherent to conventional DIF analyses
and permitting comparison of DIF statistics across test forms.