The formal seed production and supply system has for many years been unable to satisfy the seed requirements in Tanzania. This book was written basing on a study which was designed to compare the quality of the vegetable seeds produced and supplied by the informal seed sector with those produced and supplied by the formal seed sector. The informal seeds were collected from markets whereas the formal seeds were collected from stockists. Seed samples were analysed for purity, moisture content, germination capacity and vigour. All the seed lots from both sectors differed significantly in terms of the quality aspects tested with seeds from the formal seed source having higher purity than those from the informal seed source. Informal vegetable seeds had higher moisture content and germination abilities than the formal seeds. Possible explanations for these results and their implications are well discussed in the book. The book concludes, among others, that despite the significant differences between seed quality results of the vegetable seeds from both sources, vegetable seeds from the informal seed source can have as good seed quality as those from the formal seed source.