BACKGROUND: This study tested the effectiveness of a computerized mindfulness-based cognitive therapy intervention compared with computerized pain management psychoeducation in a randomized study. METHODS: Using an intention-to-treat approach, 124 adult participants who reported experiencing pain that was unrelated to cancer and of at least 6 months duration were randomly assigned to computerized mindfulness-based cognitive therapy ("Mindfulness in Action" [MIA]) or pain management psychoeducation programs. Data were collected before and after the intervention and at 6-month follow-up. RESULTS: Participants in both groups showed equivalent change and significant improvements on measures of pain interference, pain acceptance, and catastrophizing from pretreatment to posttreatment and the improvements were maintained at follow-up. Average pain intensity also reduced from baseline to posttreatment for both groups, but was not maintained at follow-up. Participants in both groups reported increases in subjective well-being, these were more pronounced in the MIA than the pain management psychoeducation group. Participants in the MIA group also reported a greater reduction in pain "right now," and increases in their ability to manage emotions, manage stress, and enjoy pleasant events on completion of the intervention. The changes in ability to manage emotions and stressful events were maintained at follow-up. CONCLUSIONS: The results of the study provide evidence that although there were equivalent changes across outcomes of interest for participants in both conditions over time, the MIA program showed a number of unique benefits. However, the level of participant attrition in the study highlighted a need for further attention to participant engagement with online chronic pain programs.