This work analyses the structure of co-ordination from two perspectives: the symmetrical properties the construction imposes on its conjuncts, and how conjuncts interact with other categories outside co-ordination with respect to agreement and other grammatical phenomena. It focuses on data from Spanish as this language is characterized by its rich pattern of overt agreement between the subject and the verb, between nouns and adjectives, and also between clitics and lexical DP objects and indirect objects. It offers a simple, unified theory of co-ordination within syntactic frameworks. It provides a succinct summary of the main analysis of co-ordination, highlighting the most important generalizations that have been made and proposes explicit analyses for long-standing problems in issues of co-ordination. The book provides a detailed description of agreement patterns in different languages (primarily Spanish), and the connection between agreement and word order and it presents a detailed account of the connection between switch-reference and co-ordination. This volume should be of interest to professionals in the field of linguistics and related fields (cognitive science, philosophy of language and so on).