This paper describes some of the military requirements for an assessment technique with which to estimate the effectiveness of the interactions that occur between military assistance program advisors and their counterparts. An experimental criterion of effectiveness, willingness to work together, is described, and estimates of its validity reported. Validity estimates are based on the relationship of the criterion scores to descriptions of the personal traits given by advisors and counterparts to one another, the extent to which they satisfy certain critical-role behaviors, and counterparts' perceptions of the advisors' primary concerns. (Author)