In Property Rights: A Re-Examination , James Penner returns to and develops a project that he has been engaged in for nearly three decades: to replace the influential 'bundle of rights' picture of property, which he regards as irredeemably flawed, with an alternative account-one that regards property as a unified entitlement. In this review article, I expound and analyse the central features of Penner's theory. I defend the view that, in its original iteration, Penner's account was trebly monistic: it regarded property as a single entitlement justified by a single human interest and protected by a single duty of non-interference. I go on to critically examine one of Penner's central ideas-that to understand property it is necessary to understand its justification. Along the way, I trace how Penner's account has evolved and explain how certain alterations have put some problems to bed while generating others.