This paper has four aims. First it distinguishes two kinds of philosophical accounts of the 'formal' features of rights: models and theories. Models outline the 'conceptually basic' types of rights (if indeed a given model deems there to be more than one), their differences, and their relationships with duties, liabilities, etc. Theories of rights posit a supposed ultimate purpose for all rights and provide criteria for determining what counts as 'a right' in the first place. Second, the paper argues that Monistic rights models (ones positing only a single basic type of right) are under-inclusive. They wrongly exclude and cannot explain relevant data, i.e., ordinary and legal linguistic practices. The third aim is to show that certain Pluralistic models are over-inclusive in terms of what they count as 'rights'. Fourth, the paper begins to touch upon, but does not provide, criteria for determining what counts as 'a right'. Two candidate factors will be addressed.