Prior to European contact, Hawaiian cultivators developed and sustained large rain-fed field systems based on sweet potato (Ipomoea batatas) and other crops. However, these intensive systems largely were abandoned in the 19th century, and there is little knowledge of how they functioned. Since 2008, we have worked to restore people and production to one such rain-fed field system at Puanui in leeward Kohala on the Island of Hawai'i using traditional knowledge, local knowledge, and experiments to understand how such systems functioned and to provide an educational and cultural resource to local communities. We encountered both climatic and biotic challenges to using traditional knowledge for restoring agricultural production. Climatically, there has been a recent drying trend and a severe 6-yr drought. Biotically, a wide range of weeds, pests, and diseases have been introduced to Hawaii since European contact. Experimental studies of cultivation practices demonstrated that rock mulching, a traditional practice, led to significantly greater yields of sweet potato than did alternative methods. More than 3000 students and community members have participated in the restoration effort and have contributed local and traditional knowledge in the process.