Participants in previous studies of brief mindfulness meditation (MM) are often tested immediately following a meditation session, making it difficult to separate several days of training from one-session effects. The current study examined the effects of a single session of 25 min of MM compared with a sham meditation (sham M) and a book-listening control. One session of both MM and sham M had a significant effect on state mindfulness compared with the control. Several mood subscales as well as total distress score on the Profile of Mood States (POMS) were also significantly different from control. However, neither meditation condition had significant effects on any of the attention and working memory tasks. These results indicate that one session of meditation was not sufficient to affect the cognitive tasks used in this study. Both MM and sham M positively affected mood states and heightened state mindfulness.