The guide presents the organisation and legal framework of the Polish social security system, as well as the role and tasks performed by the Social Insurance Institution (Zakład Ubezpieczeń Społecznych) – Poland’s largest public institution servicing this system. In particular, we present social insurance benefits provided by the Social Insurance Institution, i.e. pension benefits as well as sickness and maternity benefits. There are also discussed the basic principles of operation of the social security areas that are not administered by ZUS, such as: benefits for the family, benefits in respect of unemployment, social assistance benefits, benefits from the social insurance of farmers, benefits from the health insurance system. We also present the pension provision system for uniformed services, officers and for prosecutors and judges.