This text puts forward the main arguments for (a) why parliamentarians should put security sector reform and policy high on their political and legislative agenda and (b) why parliamentarians ought to insist on exercising oversight of the security sector and its reform. Each chapter of the book discusses a different facet of parliamentary oversight of the security sector, drawing on the expertise of its author and the organizations involved. On the whole, this publication provides a thorough and detailed overview of the main questions and challenges related to this topic, employing a vast amount of both primary and secondary sources.