{"p"=>"We examined the feasibility, acceptability and preliminary efficacy of Cognitive Behaviour Therapy for Perfectionism (CBT-P) for children delivered as an online 6-session guided parent-delivered intervention (GP-CBT-P). We conducted a two-arm randomised controlled trial comparing GP-CBT-P to waitlist for parents whose child was aged 7–12 and had elevated perfectionism. Primary outcomes were feasibility and acceptability; secondary outcomes were self-reported parental and child perfectionism, school satisfaction, happiness, stress, depressive symptoms, self-efficacy, and weight/shape concern. Assessment occurred at baseline (T1), 9- (T2, end of the intervention) and 18-weeks (T3) post-randomization. There were 89 enquiries over 14 months; 49 (54%) converted to randomisation (25 in GP-CBT-P, 24 in waitlist), and 60% of parents in the intervention group completed all 6 sessions. There were no differences between groups at baseline. Intent-to-treat analysis showed parents in GP-CBT-P had significantly lower levels of perfectionism at T2 and T3 than control (respective between groups effect sizes [ES] and 95% confidence intervals [CI] of 0.95 [0.37 to 1.53] and 0.65 [0.08 to 1.21]). Compared to control, children receiving GP-CBT-P reported significantly higher school satisfaction and academic self-efficacy, and lower stress, depression and weight/shape concerns; T3 ES ranged from 0.58 to 0.82. There were no significant differences between groups on child perfectionism. GP-CBT-P could benefit from strategies to enhance feasibility and acceptability given it promoted helpful change across parent and child self-reported outcomes. Reducing parental perfectionism may be a key driver of beneficial change in children. Further investigation with larger samples and longer-term follow-up is recommended."}