Verb agreement with a nominative element is severely constrained in Icelandic when a Quirky “subject” is present: only partial (number, not person) agreement obtains. This paper tries to account for this restriction in terms of Bonet's 1994 Person-Case-Constraint, which blocks ‘object’ person agreement when agreement with a dative element takes place. I put forward the idea that agreement obtains with Quirky subjects, but fails to show up morphologically on the verb for non-syntactic reasons. The analysis is extended to other languages, which allows me to address the issue of the nature of Quirky Case, and of inherent Case more generally.