The need for a comprehensive social security system in Tanzania s 1n response to the inadequacy of the existing system. The Inadequacy of the existing social security system is viewed on two counts, first, its coverage which leaves larger sections of the population (peasants, casual laborers, self-employed outside agriculture) uncovered. Second, its administration not only gives monopoly to the administering agencies but also limits clients (those covered) the rights to choose the type and form of social security scheme to be under. What is required in Tanzania is, a social security system which not only provides different schemes for differentiated needs of the different sections of the population but also a system which w111 provide wider choice to the differentiated sections of the Tanzania population. The proposed comprehensive social security system will be achieved through reforms in the formulation and administration of social security Policy in Tanzania. The policy reformulation process calls for institutionalization of a social security making body with wide ranging knowledge of the various contingent aspects of social Security. It is the aim of this paper to examine the inadequacies of the existing social security system in Tanzania as well as its administration, and to propose for a comprehensive social security system. In so doing the paper focuses on the genesis, scope, administration and limitations of the existing system in Tanzania, the context of social security system and the proposed comprehensive social security system.