This chapter summarizes the main findings of the study and explores how they relate to existing research. It addresses three major issues: the conceptualization of populism and classification of parties; the causes of populist voting at the individual level; and why some populist parties persist while others declined. The chapter deals with the question whether populism should be seen as a threat or rather a corrective for liberal democracy. It reviews the different models of voting and argued that the sociological model and the economic model were most suited to understand the populist voter. Then, it also focuses on the conceptualization, measurement and causes of populism in Western Europe. This brings up the question whether the results of this analysis can also inform the debate about the potential threat that populism poses to contemporary democracies. The chapter explains consolidated democracies in which populist parties were in opposition most of the time.