This chapter provides an overview of studies on multiword units of meaning that have made an impact on the creation of SciE-Lex (see Verdaguer et al. this volume). We discuss a variety of statistical, phraseological and rhetorical approaches to collocation, as well as the notion of lexical bundle (Biber et al. 1999). We also expound on the complementarity of these approaches and highlight the need for combining a range of research methods in the study of multiword units of meaning, especially if they are to be used in the development of practical instruments that can help non-native users of a language increase their phraseological competence.