Sugar cane and pineapple have dominated agriculture in Hawaii for more than 100 years. The plantation system that produced these agronomic crops is now in sharp decline, and a search is underway for horticultural crops, such as macadamia nut, papaya, and potted foliage plants, with which to diversify island agriculture. This paper, using the case study of potatoes and melons, describes the constraints encountered in establishing a 1000-acre farm enterprise on lands made available by the closing of Oahu Sugar Plantation in 1994. The major constraints were 1) a short-term lease with a clause for immediate revocation, 2) the reallocation of irrigation water from agricultural to conservation use, 3) the available plantation work force was ill-prepared for the varied tasks of horticultural production, 4) an irrigation infrastructure not compatible with vegetable production, 5) difficulty in expanding pesticide labels for local use, and 6) the absence of an institution to provide policy and technical assistance in addressing the above constraints.