In many countries, the regulations governing pension systems, hiring procedures, and job contracts differ between the public and private sectors. Public sector employees tend to have longer tenures and higher wages compared to workers in the private sector. As such, social security reforms can affect both retirement decisions and sectoral choices. We study the effects of social security reforms on retirement and sectoral behavior in an economy with multiple pension systems. We develop a general equilibrium life-cycle model with heterogeneous agents, three sectors - private formal, private informal and public - and endogenous retirement. We quantitatively assess the long-run effects of reforms being discussed and implemented around the world. Among them, we study the unification of pension systems and increasing the minimum retirement age. We calibrate our model to Brazil, where several of the retirement conditions resemble those of other countries. We find that these reforms lower the likelihood of individuals to apply to a public job and increase the profile of savings over the life cycle. In the long run, these reforms lead to higher output and capital, reduced informality, and average welfare gains. They also drastically reduce the social security deficit.