This paper constitutes a tirst attempt to pull together data and interpreta tive statements developed during a year loog investigation of social security policy in Brazil, as part of a larger ongoing comparative effort to study the relationship between social security policy and income inequality in several Latin American nations. The central hypothesis of lhe larger comparative study are (a) that social security policy tends to reinforce unequal patterns of income distribution and (b) that this effect is due to political and administrative structures which reflect the interrelationship between governments and interest groups. The article is divided into two parts: first, an historical overview of the formulation and implementation of social security policy in Brazil: and second, a discussion of the relationship between social security policy and income distribution in Brazil under both the old system in effect prior to 1964 and the new system initiated in that year. Historically, the author concludes that social security in Brazil has gone through two major overhauls during this century, in both cases in the context of strong authoritarian regimes. In both cases the restructuring of the relations between state and society in general and the state and the working class in particular were primary goals, and a clear attempt was made to give the state the upper hand in relationship to society and the working class. Throughout this period, interest groups in the classic sense have not been a source of policy initiative or innovation. Rather they have tended to react to initiatives defined from above in two ways: first, by dernanding a pre-defined recognized right and bargaining to increase their benefits vis-à-vis other groups; second, by using their power, arising in part out of control of key public institutions, to protect their privileged position by blocking or delaying attempts to reform and reorganize the system.