This study examined the effects of expressive narrative writing in 607 participants. Compared with a control group, the participants randomly assigned to write about their feelings and thoughts after the Madrid train attack on M11 report less negative emotions related to the recall of the collective trauma at a 2‐month follow‐up after the attacks. However, no effects were found on positive affect, probably because the study had only one writing session of brief duration. Stronger feelings of joy, use of positive words, and low use of negative words in the narratives predicted low emotional activation at follow