Verbs (V), adjectives (A), nouns (N) and adpositions (P) constitute the four major word classes. The present volume deals with adpositions and their projections (adpositional phrases or PPs). The general introduction in Chapter 1 provides a survey of the most distinctive syntactic, semantic and morphological characteristics of adpositions. Like the other categories, adpositions can project: in other words, they select complements and can be modified, which will be discussed in Chapter 2 and Chapter 3, respectively. After this, we will have a closer look at the syntactic uses of the adpositional phrases in Chapter 4. This study will be concluded in Chapter 5 with a discussion of the formation of pronominal PPs like er op ‘on it’, which consist of a so-called R-word like er and a preposition, and the phenomenon that these pronominal PPs can be split by extraction of the R-word. We will also address the complicated issue of co-occurrence and conflation of different types of R-words, although, strictly speaking, this goes somewhat beyond the main theme of this work.