Bulgaria has been implementing radical structural reforms to ensure economic stability and equitable growth since the end of 1989. However, a significant fall in wages, rising unemployment, a worsening old-age-dependency ratio, a decline in fertility rates, and high emigration outflows have put the social security system in Bulgaria under increasing strain. The Bulgarian authorities have responded to these trends by implementing a series of reforms designed to maintain the sustainability of the system. The aim of this chapter is to investigate broad issues concerning the pension system in Bulgaria and the economic, demographic, and social determinants that affect its sustainability. The contemporary model of the Bulgarian pension system is based on two main legislative acts: the Social Insurance Fund Act, adopted in 1996, and the Social Insurance Code, implemented in 2003. Social insurance is based on the principles of general and obligatory insurance, solidarity among the people insured, equal rights of insured people, social dialogue in the management of the social insurance system, and a fund-based organization of resources. This study employs desk research and a descriptive analysis of data to investigate the economic, demographic, and social dimensions of pension reform in Bulgaria. The findings suggest the need to further reform retirement policies because they need to be based on a cost-effective, multi-faceted policy that encompasses both pension schemes and a wider system of social protection. Furthermore, the fiscal risks resulting from demographic developments need to be considered in order to ensure the long-term sustainability of the pension system.