Objective: To evaluate the cost and cost-effectiveness of a farm-to-Special Supplemental Nutrition Programme for Women, Infants and Children (WIC) intervention to promote vegetable intake and the redemption of WIC vouchers for produce purchases at farmers’ markets.

Design: An economic analysis was undertaken using data from a pilot of the intervention. Vegetable intake was assessed with a reflection spectroscopy device (the Veggie Meter® [VM]) and via self-report. Voucher redemption was reported by WIC. Total and per participant intervention costs and cost-effectiveness ratios (expressed as cost per intervention effect) were estimated in 2019 US dollars over a 6-month period from the perspective of the agency implementing the intervention.

Setting: A large, urban WIC agency.

Participants: Participants were 297 WIC-enrolled adults.

Results: Post-intervention, VM scores, self-reported vegetable intake and voucher redemption were higher in the intervention as compared with the control study group. Over the 6-month period, intervention costs were $31 092 ($194 unit cost per participant). Relative to the control group, the intervention cost $8·10 per increased VM score per participant, $3·85 per increased cup/d of vegetables consumed per participant and $3·29 per increased percentage point in voucher redemption per participant.

Conclusions: Intervention costs and cost-effectiveness ratios compared favourably with those reported for other interventions targeting vegetable intake in low-income groups, suggesting that the programme may be cost effective in promoting vegetable purchases and consumption. As there is no benchmark against which to compare cost-effectiveness ratios expressed as cost per unit of effectiveness, conclusions regarding whether this is the case must await further research.