OBJECTIVE:A translational trial evaluated the effectiveness of screening for inhibited childhood temperament, followed by a preventive parenting program -Cool Little Kids. This study determined the cost-effectiveness from societal and health sector perspectives using trial data. METHOD:Resources to deliver the screening and parenting sessions were determined from study records. Parents completed a questionnaire reporting resources used at one-year follow-up. Standard Australian unit costs were applied. Clinical outcomes for children and parental quality adjusted life-years (QALYs) were used to calculate incremental cost-effectiveness ratios (ICERs). RESULTS:Total societal costs were lower, but non-significant for the intervention compared to the control group (mean difference -$500 p = 0.937). Total health sector costs were significantly greater (mean difference $1,956; p = 0.015). The intervention led to significantly fewer internalising symptoms (Strengths and Difficulties Questionnaire (SDQ)-emotional difficulties adjusted mean difference -0.5; p = 0.006), fewer children with SDQ-emotional symptoms in the abnormal range (24.2 % vs. 33.0 % p = .014) and fewer with diagnosed anxiety (44.2 % vs. 50.2 % p = 0.427). From the societal perspective, the intervention would likely be cost-effective. Health sector ICERs were $1,171/SDQ-emotional symptom decrease, $51/abnormal SDQ avoided and $77/anxiety case avoided. CONCLUSIONS:This economic analysis alongside an implementation study provides an early indication that Cool Little Kids may be cost-effective.