Beck et al. (2009) conducted a cross-linguistic survey of degree constructions and proposed three parameters to classify languages according to the constructions they allow and their available interpretations: 1. whether a language has degrees in its semantics (+/-DSP); 2. whether a language has degree abstraction (+/-DAP); and 3. whether a language allows the degree argument position of a gradable predicate to be overtly filled (+/-DegPP). In this talk, I provide new data from Vietnamese that tests the predictions of these parameters. A language with a positive setting for all three parameters that permits clausal comparatives should allow difference comparatives, comparisons with degrees, degree questions, direct measure phrases, and subcomparatives, and it should show negative island effects and scope ambiguities in the interpretation of DegP. Vietnamese broadly conforms to the expectations for this type of language except for one aspect: many subcomparatives are ungrammatical. After showing that Vietnamese is +DSP, +DAP, and +DegPP and that it allows clausal comparatives, I will discuss different subcomparatives that are grammatical, ungrammatical, and subject to speaker variation. I propose that these differences can be captured by positing that some Vietnamese predicates combine directly with degree arguments, while other predicates must have nhiều `much, many' or its silent counterpart μ combine with degree arguments first before this phrase combines with those predicates, an idea broadly inspired by Bresnan (1973), Grano & Kennedy (2012) and Wellwood (2012). I also propose a mandatory deletion operation that occurs in the standards of Vietnamese comparatives, forcing predicates to elide when they combine directly with DegP but allowing them to remain overt when DegP must first combine with nhiều/μ.