Schools are promising sites for the delivery of prevention and early intervention programs to reduce child and adolescent anxiety. It is unclear whether universal or targeted approaches are most effective. This review and meta-analysis examines the effectiveness of school-based indicated interventions and was registered with PROSPERO [CRD42018087628].MEDLINE, EMBASE, PsycINFO and the Cochrane Library were searched for randomised controlled trials comparing indicated school programs for child and adolescent anxiety to active or inactive control groups. Twenty original studies, with 2076 participants, met the inclusion criteria and 18 were suitable for meta-analysis. Sub-group and sensitivity analyses explored intervention intensity, delivery agent and control type. A small beneficial effect was found for indicated programs compared to controls on self-reported anxiety symptoms at post-test (g = -0.28, CI = -0.50, -0.05, k= 18). The small effect was maintained at 6 (g = -0.35, CI= -0.58, -0.13, k = 9) and 12 months (g = -0.24, CI = -0.48, 0.00, k = 4). Based on two studies, >12 month effects were very small (g = -0.01, CI= -0.38, 0.36). No differences were found based on intervention intensity, delivery agent and control type. There was evidence of publication bias and a relatively high risk of contamination in studies. Findings support the value of school based indicated programs for child and adolescent anxiety. Effects at 12 months outperform many universal programs. High quality, randomised controlled and pragmatic trials are needed, with attention control groups and beyond 12 month diagnostic assessments are needed.