Over the last decades, the pension landscape in Europe has changed substantially. Policymakers across the continent devoted particular attention to reforming pension systems, with the objective of achieving sustainability. While the pace of reform has varied, and in some the effects are not yet apparent, the scope of the reforms and their potential impact is such as to merit an in-depth assessment. In this light, this book tries to understand the contribution reforms may have made to achieving sustainability. Looking at ten EU countries, this research argues that policymakers need to adopt a more comprehensive definition of sustainability. When looking into the future, they need to reassure themselves not only that pressure on constraints is being managed properly, but also that the pension system remains effective and is in a position to achieve the goals it is expected to. The framework developed here presents one way in which policymakers can determine how best to structure their reforms. Pension systems have proven to be one of the most treasured social constructs of the twentieth century. If tackled well, reforms can ensure pensions remain socially sustainable.