The effectiveness of EQUIP on sociomoral development and recidivism reduction: A meta-analytic study

• Two multilevel meta-analyses were conducted to examine the effectiveness of EQUIP.
• EQUIP proved to be effective in enhancing sociomoral development.
• Studies in the USA showed higher treatment integrity than studies in Europe.
• Only studies in the USA were effective in reducing recidivism.
• EQUIP was most effective in reducing recidivism in females and Caucasians.

Two multilevel meta-analyses, consisting of 10 studies and 33 effect sizes (N = 796 subjects) and 6 studies and 22 effect sizes (N = 1179 subjects) were conducted to examine the effects of the EQUIP intervention on the level of sociomoral development and recidivism, respectively; moderating effects of participant, program, and study characteristics were also examined. A significant overall effect on sociomoral development was found (d = .27). The effect of EQUIP on sociomoral development was moderated by the sample size: studies with a larger sample size had smaller effect sizes. For recidivism, a non-significant overall effect size (d = .13) was attributable to strong moderator effects by gender (a significant effect for girls of d = .55), year of publication (older studies yielded smaller effect sizes), ethnicity (smaller effects in non-Caucasians), and especially region, indicating that studies conducted in the USA (showing high treatment integrity) were more effective (d = .32) than studies conducted outside the USA (showing low or negligible treatment integrity, d = − .31). These results suggest the importance of considering potential effects of study, participant characteristics, and program integrity when delivering EQUIP.