Purpose: Training and supporting homecare staff in reablement aims to change staff behavior from “doing for” to “doing with” older adults and is assumed to benefit the health and quality of life of older adults and reduce healthcare utilization and costs. This study evaluated the cost-effectiveness and cost-utility of the staff reabl ement training program “Stay Active at Home” (SAaH) from a societal perspective. Participants and Methods: An economic evaluation was embedded in a 12-month cluster randomized controlled trial. Ten Dutch homecare nursing teams participated (n = 313 staff members), of which five teams were trained in reablement and the other five provided usual care. Cost and effect data were collected from 264 older adults at baseline, 6 and 12 months. Costs included “intervention,” “healthcare,” and “patient and family” costs (collectively, societal costs) and were assessed using questionnaires and client records or estimated by bottom-up micro-costing. Effects included sedentary behavior and quality-adjusted life years (QALYs). Multiple imputed bootstrapped data were used to generate cost-effectiveness planes and acceptability curves. Results: No statistically significant differences were observed between the intervention and control group in terms of sedentary time, QALYs, and societal costs, except lower costs for domestic help in the intervention group. The probability that SAaH was cost-effective compared to usual care ranged from 7.1% to 19.9%, depending on the willingness-to-pay (WTP) (€0‒€50,000)/minute of sedentary time averted and was 5.9% at a WTP of €20,000/QALY gained. Conclusion: SAaH did not improve outcomes or reduce costs and was not costeffective from a societal perspective compared to usual care in Dutch older adults receiving homecare. Consequently, there is insufficient evidence to justify widespread implementation of the training program in its current form.