Journal of Consulting and Clinical Psychology, Vol 94(6), Jun 2026, 340-352; doi:10.1037/ccp0001011
Objective: The current randomized controlled trial (preregistered at https://osf.io/8k7xa) compared an online self-help intervention for perfectionism that allowed users to select their own skills modules to a book control condition. Method: Participants with clinically significant perfectionism (N = 114; Mage = 33.9, 52.3% White, 58.7% women) were randomly assigned to an online training (app) or active control (self-help book) condition and assessed at baseline, weekly during a 4-week intervention period, at 1-month follow-up, and at 6-month follow-up. Results: We found a smaller decrease in perfectionistic evaluative concerns in the app condition compared to the book condition (Frost Multidimensional Perfectionism Scale-Evaluative; ps = .002 to .007), but no differences were observed for perfectionistic striving (Frost Multidimensional Perfectionism Scale-Striving), psychological distress (Depression Anxiety Stress Scales), quality of life, psychological flexibility (PsyFlex), and self-compassion (Self-Compassion Scale–Short Form) by 6-month follow-up (within-group Cohen’s ds for perfectionism subscales = −0.79 to −0.42 for the app, −1.12 to −0.88 for the book). Participants in the app condition rated modules as being more helpful for meeting specific than general needs (t = −2.40, p = .021), suggesting they could “self-personalize” treatment by selecting modules that fit their needs at the time of use. We did not find significant moderation effects for any demographic or clinical variables. Conclusions: Both interventions showed similar effects over time and may serve as helpful low-intensity treatments for clinical perfectionism. Limitations include lack of a waitlist control condition, which precludes conclusions about efficacy of the study interventions beyond time effects. (PsycInfo Database Record (c) 2026 APA, all rights reserved)