The general goal of the paper is to argue for the hypothesis that, just like comparative morphemes (e.g. English -er), superlative morphemes (e.g. English -est) can take a degree clause as argument, which denotes the domain of comparison. The specific goal consists of showing that this hypothesis provides a novel solution to two controversial empirical puzzles: how to derive (i) the low reading of intensional superlatives (e.g. the reading of the longest book that John said that Tolstoy had written when John — not the speaker — evaluates the lengths of the books under consideration), and (ii) upstairs de dicto readings (e.g. the reading of John wants to climb the highest mountain when John has a specific desire of climbing achievement without any comparative content). In both cases, the superlative clause hypothesis solves previously unsolved problems because it allows split scope between -est and the gradable adjective as well as (variously partial) ellipsis of the degree clause.