An adaptive distribution-free test is proposed for the two-sample
location problem. Fi rst, the data are used to assess the tai lweight and
skewness of the underlying distributions. This leads to the selection
and then application, with the same data, of one of several common
rank tests for shift, such as the Mann-Whitney-Wilcoxon test. The
preliminary selection is made in a way that insures the testing procedure
is distribution-free. A Monte Carlo study shows that the
adaptive test has excellent power over a wide class of distributions
and is preferable to certain prominent nonadaptive tests.