A meta-analysis was conducted on 44 educational studies that used either a (labelled) Hawthorne control group, a manipulation of Hawthorne effects, or a group designed to control for the Hawthorne effect. The sample included published journal articles, ERIC documents or unpublished papers, and dissertations. The studies were coded on 20 variables, including the Hawthorne concern, Hawthorne control procedure, treatment controls, and sampling procedures. Each dependent measure was also coded on its outcome type. In most studies, the Hawthorne group was matched with the experimental group on a variable which reflected the Hawthorne concern: (1) an activity was performed to equate subjects with the experimental group's time, effort, interest, or novelty; (2) subjects were made aware that they were in an experiment; or (3) special attention was provided. Effect sizes were calculated for each treatment and for each Hawthorne group in comparison with the no-treatment control group, and for the treatment group in comparison with the Hawthorne group. Results in all but four cases were found to be nonsignificant, suggesting a database of generally poor quality. These preliminary results were consistent with previous reports of confusion surrounding artifact control. (GDC)