The effects of prenotification, ink color, and return deadline on sincerity and rates of response to mailed questionnaires concerning desirable characteristics of teachers were investigated in Thailand. Questionnaires were mailed to 800 public secondary school teachers in Bangkok. Some teachers received prenotification of the survey by mail, while others did not. The 100-item questionnaires were printed in blue, black, green, or red ink. For some questionnaires, a response rate was specified; others asked for return as soon as possible. The first mailing included a cover letter, the questionnaire, and a stamped self-addressed return envelope. The first follow-up was a reminder card. The second follow-up included a cover letter, a second copy of the questionnaire, and a stamped self-addressed return envelope. The first follow-up was sent 4 weeks after the initial mailing, and the second follow-up was sent 2 weeks after the first follow-up. The response rate of the initial mailing was 71.4%. The overall return rate was 94.9% (759 questionnaires). Sincerity of responses was judged by consistency in responding to eight pairs of parallel items measuring desirable characteristics of teachers. Significant main effects were found only for prenotification and ink color (blue and green), both of which were effective in increasing response rates and sincerity of responses at the initial mailing. Four tables present response data, and a map of Southeast Asia is provided. (SLD)