This article considers the forces behind the use of extra prepositions (by way of doubling or inserting a mismatched preposition) in relative and interrogative clause environments in Middle English. The author argues that in that period the explanation lies with both categorical and noncategorical (gradient) factors, with only the latter continuing beyond Middle English and into present-day English. Two noncategorical factors have affected English extra prepositions since the Middle English period: accessibility of wh-phrases and semantic connectedness between a verb and preposition. Semantic connectedness favors preposition stranding, while considerations of accessibility favor preposition pied-piping. The former is reflected in a bias toward adjacency of lexicalized units, the latter in a bias toward relative clauses, where the accessibility of a wh-phrase is by default low. Together, these findings provide support for lexicalist grammars that accommodate noncategorical constraints.