This book is about the democratic regulation of Canada's security and intelligence agencies at the federal level. It serves as a primer or guidebook, both for those involved in Canada's national security system and for those with an interest in it. The book proposes six values that underlie Canada's national security system and inform (or should inform) both the conduct of security service activities and the approach taken by bodies conducting democratic regulation of them. The book also discusses how democratic regulation of the security services operates in Canada, focusing on executive oversight, judicial and quasi-judicial control and scrutiny, specialized national security review, and concluding with other forms of scrutiny. It describes the background to these functions and outlines considerations properly informing their design and conduct. The book emphasizes how democratic regulation of the security services can serve as a mechanism for nudging progressive improvement in a sector often insulated from more conventional performance pressures.