In this chapter we shall examine the structure of the three main classes of group: nominal group, verbal group and adverbial group; along with a brief reference to preposition and conjunction groups. These classes of group are complexes of nominals, verbs and adverbs. They serve different functions in the clause (unless they are rankshifted and embedded in other units). In terms of the modal structure of the clause, nominal groups serve as Subj ect or Complement, verbal groups as Finite + Predicator, and adverbial groups as Adjunct; and in terms of the experiential structure, nominal groups serve in participant roles, verbal groups as Process, and adverbial groups in circumstance roles. The correspondences between class and function were illustrated earlier in Chapter 2, Figure 2-10, and will be discussed in more detail in this chapter. They are summarized in Table 6(1).