This study examines the impact of paddy irrigation investments, operations, and maintenance in Myanmar, Thailand, and Vietnam, as well as the conclusions of a performance audit of flood control schemes at three sites in Bangladesh. Findings from the review contradict the dominant model for government-operated, gravity-fed irrigation schemes in the humid tropics. The irrigation schemes are performing less well than expected at appraisal, mainly because of falling paddy prices, overoptimism about the crop area served, and project design faults. Results emphasize the value of co-production, involving pragmatic approaches to operation and maintenance under which public irrigation agencies, local authorities, and farmers work together to address specific problems and strengthen appropriate incentives.