In this paper we present an analysis of English measure noun phrases. Measure noun phrases exhibit both distributional idiosyncrasy, in that they appear in positions normally filled by degree adverbs: "a ten inch long string"; and agreement discord: "ten inches is enough", "it is ten inch/*inches long". The analysis introduces one idiosyncratic construction, the Measure Phrase Rule, which links together syntax and inflectional morphology. Combined with existing rules, in particular the Noun-noun Compound Rule, the new rule accounts for the both the distributional and agreement idiosyncrasies. The rule has been implemented and tested in the ERG, a broad-coverage grammar of English. Our analysis supports the position that broad-coverage grammars will necessarily contain both highly schematic and highly idiosyncratic rules.