The aim of this article is to define the Lithuanian public pension system reforms, influenced by the last economic crisis and social challenges (ageing processes, raising social expenses). The paper also investigates the influence that current demographic trends will exert on the financial dynamics of the pension system. Results reveal the long-term sustainability of the system, albeit at a cost of initial negative balances to be covered with public budget. Also, the system may expose pensioners to the risks of poverty and social exclusion because of low payments. It is then necessary to intensify the pension system’s reform. Policy solutions should encourage and extend employment (especially for the disadvantaged) and rebuilt trust in both public and private pension systems.