The goal of this dissertation is to study a specific type of complex word-formation, namely compounding, and its relation to the morphology-syntax interface, with the ultimate aim of gaining a better understanding of the phenomenon. Different aspects of compounding are explored in this work, of which the main questions addressed in each chapter are outlined below. The first chapter presents some evidence for the plausibility of a theory of grammar in which word syntax and phrasal syntax (which are referred to as morphology and syntax respectively) are two distinct modules within a bigger syntactic module (cf. Jackendoff 1990, 1997, 2002, Ackema & Neeleman 2004), as well as evidence for the generation of compounds within word syntax/morphology. A morphological account of compounding, based on Ackema & Neeleman's (2004) morphosyntactic competition theory, is explored, tested with some English and Romance (Catalan and Spanish) compounds and contrasted with Harley's (2004, 2008b) syntactic analysis of compounds, based on Distributed Morphology (cf. Halle & Marantz 1993, Marantz 1997a, b, 2001, 2007, a.o.). The data examined in this chapter favour the morphologically-based account over the syntactically-based account of compound formation. For example, the former account can explain contrasts like *to meat-eat and to computer-generate, while the latter cannot. The second chapter starts by establishing the existence of heads in morphology and showing their crucial role in the classification of compounds. Then, the nature of the compounding elements in English and Catalan is examined, which is followed by a brief overview of some compound classifications. The most promising classification is that of Bisetto & Scalise (2005), according to which there are three overarching macro-types of compounds: subordinate, attributive, and coordinate, each being subdivided into endocentric and exocentric types. Another level of analysis is added to their original classification and the resulting scheme is applied when carrying out an exhaustive study of compounding in English and Catalan. Although initially adopted, Bisetto & Scalise's tripartite classification changes substantially in the course of the chapter. The three macro-types of compounds are reduced to one compounding type, based on a head vs. non-head relation, from which the different interpretations arise (subordinate, attributive). The existence of coordinate compounds and exocentric compounds is argued against. The third chapter first explores Snyder's Compounding Parameter (Snyder 1995, 1996, 2001, 2002). After identifying which complex predicates must count as relevant to the parameter, its workings are considered in a few languages. The validity of the Compounding Parameter is questioned. It is concluded that a strict application of the compounding/complex-predicate parameter cannot be maintained nor can the alleged dependence of complex predicates on NN compounding. The second part of the chapter considers the possibility of a real connection between resultatives and compounding. To this end, two syntactic analyses of resultatives (Kratzer's 2005 and Mateu's 2000, 2010) are briefly reviewed. The conclusion is that compounding and resultative constructions seem to be two rather different phenomena. Finally, the question of why in some languages - like Catalan - NN compounds are productive, albeit to a lesser degree than NN compounds in a language like English, is addressed. The fourth chapter brings together the main findings of this dissertation in a compact form.