This book explores the behavior of Orange flesh Sweet potato yields and beta- Carotene content in terms of stability in different Agro ecologies. Its potential in alleviating vitamin A deficiency cannot be realized unless the cultivars exhibit good performance and stability in wider environment. Multi location field trials involving 12 orange- fleshed sweet potato varieties were conducted at six different agro-ecologies (altitude range from 495 and 1798 meters above sea level) Tanzania. Results showed that genotype and environment has influenced on beta- carotene content and yields of sweet potato roots. Sweet potato plants tend to accumulate more beta- carotene in high altitude. Utilization of sweet potato is mainly for direct human consumption, sale and animal feed in Tanzania. Consumers 'prefer varieties with high dry matter content.