High and low defensive individuals engaged in attempted thought suppression and non-suppression after viewing an emotionally stressful piece of film. As a function of suppression and non-suppression instructions, high and low defensive individuals differed from each other in the number of reported film-related thoughts. Suppression instructions had greatest effects on low defensive individuals in reducing the number of reported film-related thoughts. The effects of suppression instructions were not significant in reducing the number of film-related thoughts for high defensive individuals. High defensive individuals also reported more neutral thoughts under the suppression condition compared with the non-suppression condition. Low defensive individuals reported similar numbers of neutral thoughts under the two conditions. Effects of suppression instructions were investigated in a subsequent cognitive task that measured the level of interference produced by attempted suppression. Suppression instructions did not significantly effect the cognitive processing of participants. Theoretical and methodological implications for understanding the possible cognitive structures underlying attempted suppression are discussed in terms of the effects of defensiveness. Copyright © 2004 John Wiley & Sons, Ltd.