Common bean (Phaseolus vulgaris L.) is an important food and cash crop in Sub-Saharan Africa (SSA). It is the cheapest source of protein for human and ranks third in importance in SSA. Common bean yields in Kenya is low (700 kg/ha) compared to yield potentials of 3000 – 5000 kg/ha, mainly due to low soil fertility, Al and Mn toxicities. Continuous cropping with little or no fertilizer input has resulted in a decline in soil fertility. Organic manure at the farm level is unavailable in sufficient quantities to replenish the low soil nutrient status and synchrony of nutrient release by organic materials is difficult to obtain. Appropriate measures need to be instituted in addressing these soil and plant nutritional problems that impede sustainable food security in Kenya. The aim of the study was to determine the effects of N and P fertilizers on seed quality and yield of common bean (Phaseolus vulgaris L.). The objectives were to determine the effects and rates of N and P fertilizers on crop parameters, seed quality and yield of common bean (Phaseolus vulgaris L.). The study consisted of three field experiments in a 4 by 4 factorial experiment arranged in a randomised complete block design (RCBD) with 4 levels of N as CAN and 4 levels of P as TSP (16 treatments) conducted in Uasin Gishu, Busia and Siaya districts, one each per district. The trials were carried out for one season and data on soil, crop and seed parameters analyzed using SPSS computer package. The results of the study indicated that soils (0-15 cm depth) in the three sites were acidic (pH < 5.5). The soils were found to be generally deficient in N and P and adequate in Ca and Mg. Crop uptake of N and P depended on the initial soil N and P contents, and N and P fertilizer inputs. Applying N and P fertilizers increased soil P significantly (P < 0.05) in Uasin Gishu but not in the other sites. But soil N was not affected. Effects of N and P fertilizers on N and P uptake, height growth, trifoliate leaves, pods per plant, dry matter yield, seed yield were all significant at P < 0.05 while seed purity, seed vigour and viability, and seed moisture contents were not affected. The quality of seed in all the three sites was found to be high.