Our aim was to investigate whether four treatment features (i.e., the inclusion of parental involvement, goal-setting strategies, maintenance/relapse prevention sessions, the addition of booster sessions) were associated with posttreatment and follow-up effect size of youth cognitive behavioral therapies (yCBTs) for anxiety, depression, posttraumatic stress disorder, and obsessive-compulsive disorder in age groups spanning young children to adolescents. We conducted a random-effects meta-analysis of 106 yCBTs tested in 76 randomized clinical trials from the PracticeWise Database to examine average effects of yCBTs posttreatment and at a later follow-up assessment. We coded the use of parental involvement, goal setting, booster sessions, and maintenance/relapse prevention in each yCBT and conducted random-effects meta-regression analyses to investigate whether these treatment features were associated with yCBT effects at posttreatment as well as at follow-up. Overall, yCBTs produced large pre- to posttreatment effects (d = 1.05), 95% confidence interval [0.94, 1.15], and larger pre- to follow-up effects (d = 1.29), 95% confidence interval [1.18, 1.40]. Metaregression results indicated that parental involvement was significantly associated with larger pre- to posttreatment effect sizes as well as pre- to follow-up effect sizes. Booster sessions, goal setting, and maintenance/relapse prevention were not significantly related to effect sizes at posttreatment or follow-up. Parental involvement may be helpful for maximizing long-term effectiveness of yCBT. Future studies should investigate for whom and under what conditions inclusion of yCBT treatment features is related to the durability of treatment gains.