This study examined the effectiveness of a mindfulness-based bibliotherapy intervention to reduce perfectionism and associated distress. Sixty-three individuals were randomly assigned to the intervention or wait-list control group. The intervention group completed measures of perfectionism, perceived stress, affect, and mindfulness before receiving and reading the self-help book over the course of 6 weeks and then completing the measures again. They also completed the measures 6 weeks following the conclusion of the intervention. The wait-list control group completed the same measures 6 weeks apart. Compared to the wait-list control group, the intervention group made greater gains over time on measures of perfectionism and perceived stress. Both groups evidenced decreased negative affect. Among the intervention group, all gains were maintained at follow-up, along with additional decreases in negative affect. The intervention evidenced fidelity to its theoretical approach via increases in levels of mindfulness across time. Results have implications for future investigations of mindfulness-based self-help interventions and the treatment of perfectionism and associated distress via mindfulness approaches.