The aims of this study were to (a) identify the predictors of attrition from a fully self-directed intervention, and (b) to test whether an intervention to increase gratitude is an effective way to reduce body dissatisfaction. Participants (N=479, from the United Kingdom) aged 18-76 years took part in a self-help study via the Internet and were randomized to receive one of two interventions, gratitude diaries (n=130), or thought monitoring and restructuring (n=118) or a waitlist control (n=231) for a two week body dissatisfaction intervention. The gratitude intervention (n=40) was as effective as monitoring and restructuring (n=22) in reducing body dissatisfaction, and both interventions were significantly more effective than the control condition (n=120). Participants in the gratitude group were more than twice as likely to complete the intervention compared to those in the monitoring and restructuring group. Intervention content, baseline expectancy and internal locus of control significantly predicted attrition. This study shows that a gratitude intervention can be as effective as a technique commonly used in cognitive therapy and is superior in retaining participants. Prediction of attrition is possible from both intervention content and psychological variables. Copyright (c) 2010 Elsevier Ltd. All rights reserved.