This paper investigates core semantic properties that distinguish between different types of gradable adjectives and the effect of context on their interpretation. We contend that all gradable adjectives are interpreted relative to a comparison class (van Rooij 2011), and that it is the nature of the comparison class that constitutes the main semantic difference between their subclasses: some adjectives select a class comprised of counterparts of the individual of which the adjective is predicated, while others – an extensional category of this individual. We propose, following Kennedy (2007), that the standard of membership is selected according to a principle of economy whereby an interpretation relative to a maximum or a minimum degree within a comparison class takes precedence over one relative to an arbitrary point. This proposal captures so-called "standard shift" effects, that is, the influence of context on the interpretation of gradable adjectives from all subclasses, whether in their positive form or when modified by degree adverbials. Additionally, this proposal captures cases of apparent lack of context sensitivity (e.g. intuitive inference patterns, unacceptability of for-phrases, etc.). Finally, we hypothesize that the type of comparison class is aligned with the well known distinction between stage-level and individual-level predicates.