Key to this chapter is a focus on what variation characterises three morphosyntactic aspects within the grammar of Arabic varieties that are traditionally classified as ‘western’. The domains investigated are: negation, particularly the differences in the employment of (sentential) pronominal negation; the differences in the complementiser form that introduces complement clauses; and the realisation of existential constructions, where the variation observed within this set of varieties, ranging from the ones spoken in Mauritania to Libya, and in Malta, pans out Freeze’s (1992) threefold typology. The bird’s-eye view of the existing variation demonstrates that geographical proximity does not necessitate the prevalence of similar alignments in the behaviours observed.