This dissertation investigates scalarity in the nominal domain through the study of a subset of prenominal adverbial adjectives in Spanish, adjectives of veracity (AVs; verdadero ‘true’, auténtico ‘authentic’) and adjectives of completeness (ACs; completo ‘complete’, total ‘total’, absoluto ‘absolute’). Its aim is to contribute to the understanding of the values associated with prenominal position in Romance, the parallelism between adverbial and adjectival modification, and the manifestations of scalarity in nouns. The analysis of AVs is used to explore conceptual gradability. It is shown that the relevant factor for AVs to combine with a noun is vagueness. I propose that AVs operate over the contextual parameters involved in the determination of the interpretation of the predicate. In particular, AVs state that the individual belongs in the denotation of the noun in all the relevant contexts. This has the effect of picking up a representative individual of the category, and accounts for the intensifier and metalinguistic readings of AVs. The factors that affect the ordering in the extension of the noun, especially typicality and subjectivity, and the grammatical consequences this has for the distribution of AVs are also addressed. Although the ordering is shown to have linguistic effects, it is argued not to be grammatically represented. That is, this kind of scalarity is conceptual, not lexical. Finally, the analysis is extended to the adverbs of veracity in their modification of adjectives and verbs. The study of ACs serves to discuss grammatical gradability. Starting from the observation that adverbs of completeness are degree modifiers sensitive to scale maximums, it is argued that the correlate adjectives have the same properties and should be analyzed as degree modifiers. The chapter consists of three case studies of nouns that can be modified by ACs. First, property concept nouns (libertad ‘freedom’) are shown to share the scale structure with their cognate adjectives. ACs only occur with those related to total adjectives. These facts are accounted for by adopting a view of property concept nouns as predicates of portions of substances and having the degree argument introduced externally. Second, aspectual inheritance in the nominalizations of incremental theme verbs (destrucción ‘destruction’) and degree achievements (oscurecimiento ‘darkening’) is tackled. I demonstrate that ACs are restricted to telic eventive nominalizations and behave as maximality modifiers. The analysis accounts for these degree uses by combining a constructionist approach to the syntax of nominalizations and a degree approach to aspect for their semantics. Third, ACs display a mixed behavior with respect to their maximality when combined with evaluative nouns (idiota ‘idiot’). This is a consequence of the semantics of evaluative nouns, which are argued to denote extreme gradable properties and include an expressive component. The results provide support for a richer representation of nouns in combination with a two-domain approach to adnominal adjectives. AVs and ACs and their correspondent adverbs are shown to be two morphological variants of the same intensifier and to be restrictive, as opposed to the non-restrictive readings prenominal qualitative adjectives receive in Romance. Regarding scalarity in the nominal domain, it can be concluded that many factors interact to produce scalar effects, but only a few of them constitute real manifestations of lexical gradability. On the one hand, typicality interacts with vagueness and subjectivity, but the ordering is not grammatically represented. On the other, only evaluative nouns are argued to be lexically gradable. In the other cases, degree arguments are introduced by specialized heads, either related to measurement or to aspect. This creates a continuum of nominals, from the most adjective-like to non-gradable, with property concept nouns and eventive nominalizations placed halfway between them.