When it comes to party institutionalisation – at least for entrepreneurial right-wing protest parties -- leadership matters! That is the primary takeaway from this book. Of the hundreds of new parties that have formed since the 1970s, many have fallen by the wayside, but others have gone on to reach institution-hood. And some of the latter have then met with decay and de-institutionalisation. The experiences of the Progress Parties of Denmark and Norway – both of which institutionalised and one of which then de-institutionalised – shed important light on both topics. While focusing particularly on those two cases, the authors develop conceptual and theoretical frameworks that are broadly applicable, as demonstrated in the final chapter and in an elaborate appendix.