Problems in the interpretation of results of studies in which control groups are used are illustrated in a follow‐up study. Subjects who had been counseled over a four‐year period at the Research and Guidance Laboratory for Superior Students at the University of Wisconsin were followed up four years after high school graduation and their performances were compared with those of the members of a control or comparison group. The results are presented and the adequacy of the control group technique is discussed. The validity is questioned of the commonly accepted procedure of selecting control group subjects on the basis of theircurrentcomparability with experimental subjects without adequate history of their development toward that sta