The different social welfare systems have to face important challenges, as the increase in life expectancy and the decline in fertility rates and mortality. The expansive demographic pyramids at the beginning of the last century have resulted in constricting pyramids that show the ageing of the population. For this reason, the sustainability of the pensions is at the heart of the political debate in many countries, both developed and developing countries.
The article analyses the main characteristics of the most representative countries of each existing model, with particular attention to those in which reforms susceptible of being exported have been implemented. Each comparison between systems will always be controversial due to the fact that each of them has evolved from hardly comparable specific historical, economic, political, social and cultural circumstances.