Factors affecting the return rate of a mailed questionnaire were investigated. A survey was mailed to 196 students who had dropped out of home study courses offered by a distance education university. The effects of personalizing the cover letter and of including anonymous pre-coded personal information on the questionnaire were studied in a 2 X 2 factorial design which also allowed for an interaction effect. Reminder cards were sent two weeks later. All questionnaires contained pre-coded personal data. There were four treatment conditions: (1) personal letter and no option to remove pre-coded personal data; (2) personal letter and option to remove data; (3) formal letter and no option to remove data; and (4) formal letter and option to remove data. Thirty-nine percent of the questionnaires were returned. Results showed no interactive effect between the kind of cover letter sent and whether or not subjects were given the option of tearing off the pre-coded personal data. In addition, respondents who were given the option to remove the pre-coded data did not exercise that option. There was no difference in the response rate according to the type of cover letter or whether or not pre-coded information could be removed. (GDC)