This paper studies the distinction that was proposed in previous works between total and partial adjectives. In pairs of adjectives such as safe-dangerous, clean-dirty and healthy-sick, the first ("total") adjective describes lack of danger, dirt, malady etc., while the second ("partial") adjective describes the existence of such properties. It is shown that the semantics of adjective phrases with modifiers such as almost, slightly, and completely is sensitive to whether the adjective is total or partial. The interpretation of such modified constructions is accounted for using a novel scale structure for total and partial adjectives. It is proposed that the standard value of a total adjective is always fixed as the lower bound of the corresponding partial adjective. By contrast, the standard value of partial adjectives can take any point on the relative scale. The effects of this theoretical distinction on the behavior of modified constructions are studied in detail, and their ramifications for the semantic theory of adjectives are discussed. Some other phenomena are surveyed that show evidence for total and partial adjectival constructions with various comparatives and exceptive phrases.